Viral Video Platform Specifications (2025-2026) Skill

CRITICAL GUIDELINES

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Documentation Guidelines

NEVER create new documentation files unless explicitly requested by the user.

Viral Video Platform Specifications (2025-2026)

Complete reference for all major short-form video platforms with FFmpeg encoding presets.

Quick Reference Table

| Platform | Aspect | Resolution | Max Duration | Max Size | Codec | Audio | |----------|--------|------------|--------------|----------|-------|-------| | TikTok | 9:16 | 1080x1920 | 10 min | 287 MB | H.264 | AAC 128k | | YouTube Shorts | 9:16 | 1080x1920 | 60 sec | 256 GB | H.264/VP9 | AAC 192k | | Instagram Reels | 9:16 | 1080x1920 | 90 sec | 4 GB | H.264 | AAC 128k | | Facebook Reels | 9:16 | 1080x1920 | 90 sec | 4 GB | H.264 | AAC 128k | | Snapchat Spotlight | 9:16 | 1080x1920 | 60 sec | 300 MB | H.264 | AAC | | Twitter/X | 9:16 | 1080x1920 | 2 min 20 sec | 512 MB | H.264 | AAC 128k | | Pinterest Idea Pins | 9:16 | 1080x1920 | 60 sec | 2 GB | H.264 | AAC | | LinkedIn | 9:16/1:1 | 1080x1920 | 10 min | 5 GB | H.264 | AAC |

TikTok Specifications

Technical Requirements (2025-2026)

| Specification | Requirement | Notes | |---------------|-------------|-------| | Aspect Ratio | 9:16 (vertical) - REQUIRED | Fills mobile screen | | Resolution | 1080x1920 (recommended), min 720x1280 | TikTok compresses 4K anyway | | Video Codec | H.264 (required) | HEVC transcoded to H.264 | | Audio Codec | AAC | High-quality audio critical | | Audio Bitrate | 128-192 kbps | Higher = better | | Audio Sample Rate | 44100 Hz (48000 Hz accepted) | 44.1kHz standard | | Audio Loudness | -10 to -12 LUFS | Louder wins on mobile | | True Peak | -1.5 dBTP max | Prevents distortion | | Frame Rate | 24-60 fps (30 fps recommended) | 60fps for sports/action only | | Pixel Format | yuv420p (required) | 8-bit color, Rec.709 | | Color Space | Rec.709 (SDR) | Turn off HDR before upload | | Max File Size | 287 MB (iOS), 72 MB (Android web) | ~500 MB desktop | | Max Duration | 10 minutes | Optimal: 21-34s | | Optimal Duration | 21-34 seconds | Highest completion rate | | Min Duration | 3 seconds | Platform minimum | | Keyframe Interval | 2 seconds (60-90 frames at 30fps) | Every 2-3 seconds |

Optimal Encoding Parameters (2025-2026)

Bitrate Recommendations (VBR):

24 fps: 4-6 Mbps
30 fps: 6-8.5 Mbps (sweet spot: 6-8 Mbps)
60 fps: 8-12 Mbps

CRF Values:

CRF 21-23: Optimal quality/size balance
Below CRF 21: Diminishing returns (TikTok recompresses)
Above CRF 24: Noticeable quality loss on mobile

Preset Selection:

fast: Quick encoding, good quality (recommended for batch)
medium: Better compression (default)
slow: Best quality (use for hero content)

FFmpeg Preset (Updated 2025-2026)

# TikTok optimized encoding - 2025-2026 specs
ffmpeg -i input.mp4 \
  -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black,setsar=1,fps=30" \
  -c:v libx264 -preset medium -crf 22 -profile:v high -level 4.1 \
  -x264-params "keyint=60:min-keyint=30:scenecut=0" \
  -c:a aac -b:a 192k -ar 44100 -ac 2 \
  -af "loudnorm=I=-11:TP=-1.5:LRA=11" \
  -pix_fmt yuv420p \
  -movflags +faststart \
  -max_muxing_queue_size 1024 \
  -t 34 \
  output_tiktok.mp4

Two-Pass Encoding for Precise Bitrate Control

# Pass 1
ffmpeg -y -i input.mp4 \
  -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black,fps=30" \
  -c:v libx264 -preset medium -b:v 7M -maxrate 8M -bufsize 16M \
  -profile:v high -level 4.1 -pass 1 -an -f null /dev/null

# Pass 2
ffmpeg -i input.mp4 \
  -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black,fps=30" \
  -c:v libx264 -preset medium -b:v 7M -maxrate 8M -bufsize 16M \
  -profile:v high -level 4.1 -pass 2 \
  -c:a aac -b:a 192k -ar 44100 \
  -af "loudnorm=I=-11:TP=-1.5:LRA=11" \
  -pix_fmt yuv420p -movflags +faststart \
  output_tiktok.mp4

Algorithm Insights (2025-2026)

Hook Window: 1.3 seconds to capture attention
Optimal Length: 21-34 seconds for highest completion
Captions: 80% boost in engagement when visible
Trending Audio: 88% say it helps discoverability
Post Frequency: 1-3x daily for growth phase

YouTube Shorts Specifications

Technical Requirements (2025-2026)

| Specification | Requirement | Notes | |---------------|-------------|-------| | Aspect Ratio | 9:16 (vertical) - REQUIRED | Strictly enforced for Shorts shelf | | Resolution | 1080x1920 (recommended), min 1920px on short side | Limited to 1080p playback | | Video Codec | H.264, VP9, HEVC (VP9 preferred by algorithm) | YouTube transcodes to VP9/AV1 | | Audio Codec | AAC, Opus (Opus for VP9) | AAC-LC most compatible | | Audio Bitrate | 192-384 kbps | YouTube recommends 384k stereo | | Audio Sample Rate | 48000 Hz preferred | Match video production standard | | Audio Loudness | -13 to -15 LUFS | YouTube normalizes to -14 LUFS | | True Peak | -1 to -3 dB | Recommended: -1.5 dBTP | | Frame Rate | 24-60 fps (30 fps recommended) | Upload at source frame rate | | Pixel Format | yuv420p (SDR), yuv420p10le (HDR) | Rec.709 color space for SDR | | Max File Size | 256 GB (practical: 20-100 MB for Shorts) | Higher bitrate = better post-compression quality | | Max Duration | 60 seconds (HARD LIMIT) | Strict enforcement | | Optimal Duration | 50-60 seconds | Maximizes watch time metric | | Min Duration | ~15 seconds recommended | Shorter = harder to rank | | Color Space | Rec.709 (SDR), Rec.2100 (HDR only) | Consistent colors across devices |

Optimal Encoding Parameters (2025-2026)

Bitrate Recommendations (VBR):

1080p30: 8 Mbps (YouTube official recommendation)
1080p60: 12 Mbps

CRF Values:

CRF 18-20: High quality (hero content, archival)
CRF 20-22: Optimal quality/size (recommended)
CRF 23+: Acceptable for less critical content

Preset Selection:

slow: Best quality, longer encode (recommended for uploads)
medium: Good balance for batch processing
fast: Quick turnaround, slightly larger files

FFmpeg Preset - H.264 (Updated 2025-2026)

# YouTube Shorts H.264 encoding - maximum compatibility
ffmpeg -i input.mp4 \
  -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black,setsar=1,fps=30" \
  -c:v libx264 -preset slow -crf 20 -profile:v high -level 4.2 \
  -x264-params "keyint=60:min-keyint=30:scenecut=40" \
  -c:a aac -b:a 192k -ar 48000 -ac 2 \
  -af "loudnorm=I=-14:TP=-1.5:LRA=11" \
  -pix_fmt yuv420p \
  -colorspace bt709 -color_primaries bt709 -color_trc bt709 \
  -movflags +faststart \
  -max_muxing_queue_size 1024 \
  -t 59 \
  -metadata title="Your Shorts Title" \
  -metadata comment="#Shorts" \
  output_shorts.mp4

Two-Pass Encoding for Optimal Quality

# Pass 1 - Analysis
ffmpeg -y -i input.mp4 \
  -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black,fps=30" \
  -c:v libx264 -preset slow -b:v 8M -profile:v high -level 4.2 \
  -pass 1 -an -f null /dev/null

# Pass 2 - Encode
ffmpeg -i input.mp4 \
  -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black,fps=30" \
  -c:v libx264 -preset slow -b:v 8M -profile:v high -level 4.2 \
  -pass 2 \
  -c:a aac -b:a 192k -ar 48000 \
  -af "loudnorm=I=-14:TP=-1.5:LRA=11" \
  -pix_fmt yuv420p -movflags +faststart \
  -metadata comment="#Shorts" \
  output_shorts.mp4

FFmpeg Preset (VP9 - Higher Quality)

# YouTube Shorts VP9 encoding (preferred by YouTube)
ffmpeg -i input.mp4 \
  -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black,setsar=1" \
  -c:v libvpx-vp9 -crf 25 -b:v 0 -deadline good -cpu-used 2 \
  -c:a libopus -b:a 192k -ar 48000 \
  -row-mt 1 \
  -t 59 \
  output_shorts.webm

Algorithm Insights (2025-2026)

Completion Rate: 80-90% = algorithm boost
Optimal Length: 50-60 seconds maximizes watch time
First 3 Seconds: Critical for retention
Consistency: Daily posting recommended for growth
Thumbnail: Custom thumbnails increase CTR 30%+

Instagram Reels Specifications

Technical Requirements (2025-2026)

| Specification | Requirement | Notes | |---------------|-------------|-------| | Aspect Ratio | 9:16 (preferred), 4:5, 1:1 accepted | 9:16 fills screen, recommended | | Resolution | 1080x1920 (recommended), min 720p | No 4K support | | Video Codec | H.264 | Instagram transcodes all uploads | | Audio Codec | AAC (AAC-LC preferred) | Superior to MP3 | | Audio Bitrate | 128-192 kbps | Higher quality recommended | | Audio Sample Rate | 44100-48000 Hz | 44.1kHz or 48kHz | | Audio Loudness | -10 to -12 LUFS | Louder = better mobile experience | | True Peak | -1 dBTP recommended | Prevents clipping | | Frame Rate | 30 fps recommended (max 60) | 30fps optimal for compatibility | | Pixel Format | yuv420p | Square pixels, fixed frame rate | | Max File Size | 650 MB (<10 min), 4 GB (longer) | Practical: 50-200 MB | | Max Duration | 15 minutes (uploaded), 3 min (in-app 2025) | In-app recording: 90s before Jan 2025 | | Optimal Duration | 7-15 seconds (casual), 15-30s (tutorial) | First 3 seconds critical | | Min Duration | 3 seconds | Platform minimum | | Cover Image | 1080x1920, JPEG | Custom thumbnail increases engagement |

Optimal Encoding Parameters (2025-2026)

Bitrate Recommendations (VBR):

Standard Quality: 3,500-5,000 kbps
High Quality: 5,000-10,000 kbps (recommended for best results)

CRF Values:

CRF 21-23: Optimal balance
CRF 20: High quality for hero content
CRF 24+: Avoid (visible compression on mobile)

Preset Selection:

fast: Quick batch encoding
medium: Recommended balance
slow: Best quality (diminishing returns after Instagram recompression)

Safe Zones (2025-2026)

Top safe zone: Keep text/graphics below top 14%
Bottom safe zone: Avoid bottom 35% (UI overlays)
Side safe zones: 6% margin on each side
Text placement: Upper middle 2/3 of frame safest

FFmpeg Preset (Updated 2025-2026)

# Instagram Reels optimized encoding - high quality
ffmpeg -i input.mp4 \
  -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black,setsar=1,fps=30" \
  -c:v libx264 -preset medium -crf 22 -profile:v high -level 4.1 \
  -x264-params "keyint=60:min-keyint=30:scenecut=40" \
  -c:a aac -b:a 192k -ar 44100 -ac 2 \
  -af "loudnorm=I=-11:TP=-1.5:LRA=11" \
  -pix_fmt yuv420p \
  -movflags +faststart \
  -t 30 \
  output_reels.mp4

Bitrate-Controlled Encoding

# Instagram Reels with precise bitrate (5-10 Mbps range)
ffmpeg -i input.mp4 \
  -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black,fps=30" \
  -c:v libx264 -preset medium -b:v 8M -maxrate 10M -bufsize 20M \
  -profile:v high -level 4.1 \
  -c:a aac -b:a 192k -ar 44100 \
  -af "loudnorm=I=-11:TP=-1.5:LRA=11" \
  -pix_fmt yuv420p -movflags +faststart \
  output_reels_bitrate.mp4

Algorithm Insights (2025-2026)

Optimal Length: 7-15 seconds for casual, 15-30 for tutorial
First 3 Seconds: Must hook immediately
Trending Audio: Significant boost in reach
Hashtags: 3-5 relevant hashtags optimal
Post Time: When followers most active

Facebook Reels Specifications

Technical Requirements (2025-2026)

| Specification | Requirement | Notes | |---------------|-------------|-------| | Aspect Ratio | 9:16 (recommended), any supported | All videos = Reels as of June 2025 | | Resolution | 1440x2560 (official), 1080x1920 (practical) | Facebook recommends higher res | | Video Codec | H.264, H.265, VP9, AV1 | H.264 most compatible | | Compression | H.264, Closed GOP (2-5s) | Progressive scan, 4:2:0 chroma | | Audio Codec | AAC (stereo) | AAC Low Complexity preferred | | Audio Bitrate | 128 kbps minimum, 192k recommended | Facebook supports up to 384k | | Audio Sample Rate | 48000 Hz | 48kHz official recommendation | | Audio Loudness | -13 LUFS | Facebook normalizes to -13 LUFS | | True Peak | -1 dBTP | Prevent distortion | | Frame Rate | 30 fps or higher recommended | Match source frame rate | | Pixel Format | yuv420p | 8-bit color | | Max File Size | 4 GB | Practical: 50-300 MB | | Max Duration | No limit (as of June 2025) | Reels: 3-90 seconds optimal | | Optimal Duration | 15-30 seconds | Engagement sweet spot | | Min Duration | 3 seconds | Reel minimum |

Optimal Encoding Parameters (2025-2026)

Bitrate Recommendations:

1080p H.264: 5-8 Mbps
4K H.264: 35-45 Mbps (up to 45 Mbps supported)
Recommended for Reels: 6-10 Mbps at 1080p

CRF Values:

CRF 20-22: High quality
CRF 23: Good balance (recommended)
CRF 24+: Acceptable for casual content

Safe Zones:

Top: Leave 14% clear
Bottom: Avoid 35% (UI elements)
Sides: 6% margin each side

FFmpeg Preset (Updated 2025-2026)

# Facebook Reels optimized encoding - 2025-2026
ffmpeg -i input.mp4 \
  -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black,setsar=1,fps=30" \
  -c:v libx264 -preset medium -crf 22 -profile:v high -level 4.1 \
  -x264-params "keyint=60:min-keyint=30:scenecut=40" \
  -c:a aac -b:a 192k -ar 48000 -ac 2 \
  -af "loudnorm=I=-13:TP=-1:LRA=11" \
  -pix_fmt yuv420p \
  -movflags +faststart \
  -t 30 \
  output_fb_reels.mp4

High-Quality Preset (Bitrate-Controlled)

# Facebook Reels - high quality with bitrate control
ffmpeg -i input.mp4 \
  -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black,fps=30" \
  -c:v libx264 -preset medium -b:v 8M -maxrate 10M -bufsize 20M \
  -profile:v high -level 4.1 \
  -c:a aac -b:a 192k -ar 48000 -ac 2 \
  -af "loudnorm=I=-13:TP=-1:LRA=11" \
  -pix_fmt yuv420p -movflags +faststart \
  output_fb_reels_hq.mp4

Algorithm Insights (2025-2026)

Cross-Post: Instagram Reels can be shared to Facebook
Original Content: Watermark-free content preferred
Engagement: Comments boost reach significantly
Optimal Length: 15-30 seconds

Snapchat Spotlight Specifications

Technical Requirements

| Specification | Requirement | |---------------|-------------| | Aspect Ratio | 9:16 (required) | | Resolution | 1080x1920 | | Video Codec | H.264 | | Audio Codec | AAC | | Frame Rate | 24-30 fps | | Pixel Format | yuv420p | | Max File Size | 300 MB | | Max Duration | 60 seconds | | Min Duration | 5 seconds |

FFmpeg Preset

# Snapchat Spotlight optimized encoding
ffmpeg -i input.mp4 \
  -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black,setsar=1,fps=30" \
  -c:v libx264 -preset fast -crf 24 -profile:v main -level 4.0 \
  -c:a aac -b:a 128k -ar 44100 -ac 2 \
  -pix_fmt yuv420p \
  -movflags +faststart \
  -fs 300M \
  -t 60 \
  output_spotlight.mp4

Twitter/X Video Specifications

Technical Requirements

| Specification | Requirement | |---------------|-------------| | Aspect Ratio | 9:16, 16:9, 1:1 | | Resolution | 1080x1920 (9:16), 1920x1080 (16:9) | | Video Codec | H.264 | | Audio Codec | AAC | | Audio Bitrate | 128 kbps | | Audio Sample Rate | 44100 Hz | | Frame Rate | 30-60 fps (40 max for 1080p) | | Pixel Format | yuv420p | | Max File Size | 512 MB | | Max Duration | 2 min 20 sec (140 seconds) |

FFmpeg Preset

# Twitter/X optimized encoding
ffmpeg -i input.mp4 \
  -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black,setsar=1,fps=30" \
  -c:v libx264 -preset fast -crf 23 -profile:v high -level 4.1 \
  -c:a aac -b:a 128k -ar 44100 -ac 2 \
  -pix_fmt yuv420p \
  -movflags +faststart \
  -fs 512M \
  -t 140 \
  output_twitter.mp4

Multi-Platform Export Script

#!/bin/bash
# export_all_platforms.sh - Export video for all platforms at once

INPUT="$1"
BASENAME=$(basename "$INPUT" .mp4)

echo "Exporting $INPUT for all platforms..."

# TikTok
ffmpeg -i "$INPUT" \
  -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black" \
  -c:v libx264 -preset fast -crf 23 \
  -c:a aac -b:a 128k -ar 44100 \
  -pix_fmt yuv420p -movflags +faststart \
  -t 60 \
  "${BASENAME}_tiktok.mp4" &

# YouTube Shorts
ffmpeg -i "$INPUT" \
  -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black" \
  -c:v libx264 -preset fast -crf 22 \
  -c:a aac -b:a 192k -ar 48000 \
  -pix_fmt yuv420p -movflags +faststart \
  -t 59 \
  "${BASENAME}_shorts.mp4" &

# Instagram Reels
ffmpeg -i "$INPUT" \
  -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black,fps=30" \
  -c:v libx264 -preset fast -crf 23 \
  -c:a aac -b:a 128k -ar 44100 \
  -pix_fmt yuv420p -movflags +faststart \
  -t 90 \
  "${BASENAME}_reels.mp4" &

# Snapchat Spotlight
ffmpeg -i "$INPUT" \
  -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black,fps=30" \
  -c:v libx264 -preset fast -crf 24 \
  -c:a aac -b:a 128k -ar 44100 \
  -pix_fmt yuv420p -movflags +faststart \
  -fs 300M -t 60 \
  "${BASENAME}_spotlight.mp4" &

# Twitter/X
ffmpeg -i "$INPUT" \
  -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black,fps=30" \
  -c:v libx264 -preset fast -crf 23 \
  -c:a aac -b:a 128k -ar 44100 \
  -pix_fmt yuv420p -movflags +faststart \
  -t 140 \
  "${BASENAME}_twitter.mp4" &

wait
echo "All platform exports complete!"
ls -lh "${BASENAME}_*.mp4"

File Size Optimization

Calculate Target Bitrate for File Size

# Formula: bitrate = (target_size_MB * 8192) / duration_seconds - audio_bitrate

# Example: 50MB file, 60 seconds, 128kbps audio
# Video bitrate = (50 * 8192) / 60 - 128 = 6697 kbps

ffmpeg -i input.mp4 \
  -vf "scale=1080:1920" \
  -c:v libx264 -b:v 6500k -maxrate 7000k -bufsize 14000k \
  -c:a aac -b:a 128k \
  -pix_fmt yuv420p -movflags +faststart \
  output_sized.mp4

Two-Pass Encoding for Exact Size

# Pass 1
ffmpeg -y -i input.mp4 \
  -vf "scale=1080:1920" \
  -c:v libx264 -b:v 6500k -pass 1 -an -f null /dev/null

# Pass 2
ffmpeg -i input.mp4 \
  -vf "scale=1080:1920" \
  -c:v libx264 -b:v 6500k -pass 2 \
  -c:a aac -b:a 128k \
  -movflags +faststart \
  output_2pass.mp4

Platform Comparison: Algorithm Factors

| Factor | TikTok | Shorts | Reels | Priority | |--------|--------|--------|-------|----------| | Hook (1-3s) | Critical | Critical | Critical | #1 | | Completion Rate | High | Highest | High | #1 | | Watch Time | High | Highest | Medium | #2 | | Shares | High | Medium | High | #3 | | Comments | High | Medium | High | #3 | | Saves | Medium | Medium | High | #4 | | Likes | Medium | Low | Medium | #5 | | Captions | 80% boost | Helpful | Important | Must-have | | Trending Audio | Essential | N/A | Important | Platform-specific | | Original Content | Preferred | Required | Preferred | Important | | Posting Frequency | 1-3x/day | Daily | Daily | Consistency |

Verification Commands

# Verify platform compliance
verify_platform() {
    local file=$1
    echo "=== Checking: $file ==="
    ffprobe -v error -select_streams v:0 \
      -show_entries stream=width,height,codec_name,pix_fmt,r_frame_rate,bit_rate \
      -show_entries format=duration,size,bit_rate \
      -of default=noprint_wrappers=1 "$file"

    # File size in MB
    size_mb=$(ls -l "$file" | awk '{print $5/1024/1024}')
    echo "File Size: ${size_mb}MB"
}

verify_platform output_tiktok.mp4

Codec Comparison for Short-Form Video (2025-2026)

H.264 vs H.265 vs AV1 Decision Matrix

| Codec | Compression | Encoding Speed | Platform Support | Recommendation | |-------|-------------|----------------|------------------|----------------| | H.264 | Baseline | Fast | Universal | Primary choice - all platforms transcode to H.264 anyway | | H.265 | 40-50% better | 5-10x slower | Limited mobile | Avoid - platforms transcode, licensing issues | | AV1 | 50-60% better | 5-10x slower | Growing (YouTube, Netflix) | Future-proof for web, not for social uploads | | VP9 | 40% better | Slower | YouTube preferred | Only for YouTube Shorts WebM uploads |

Platform Codec Recommendations

| Platform | Upload Codec | Platform Transcodes To | Best Practice | |----------|--------------|------------------------|---------------| | TikTok | H.264 | H.264 | Always H.264 | | YouTube Shorts | H.264 or VP9 | VP9, AV1, H.264 | H.264 for compatibility, VP9 for quality | | Instagram | H.264 | H.264 | H.264 only | | Facebook | H.264 | H.264, VP9 | H.264 most reliable |

Key Insight: All platforms re-encode uploads. Upload high-quality H.264 to give platform encoders the best source material. H.265/AV1 add encoding time with no benefit for social media.

Color Grading for Viral Appeal (2025-2026)

Mobile-Optimized Color Parameters

Research-backed findings: Bold, saturated colors perform 2-3x better on mobile screens.

| Parameter | Conservative | Viral-Optimized | Bold/Stylized | |-----------|--------------|-----------------|---------------| | Saturation | 1.0-1.1 | 1.1-1.2 | 1.3-1.5 | | Contrast | 1.0-1.1 | 1.15-1.25 | 1.3-1.4 | | Brightness | 0 to +0.05 | -0.02 to 0 | -0.05 (cinematic) | | Sharpness | Unsharp 5:5:0.3 | Unsharp 5:5:0.6 | Unsharp 5:5:1.0 |

Viral Color Grading Presets

1. Bold & Eye-Popping (Maximum Engagement)

# High saturation, punchy contrast for maximum mobile impact
ffmpeg -i input.mp4 \
  -vf "eq=saturation=1.2:contrast=1.2:brightness=-0.02,unsharp=5:5:0.8" \
  -c:v libx264 -preset medium -crf 22 \
  output_bold.mp4

2. Orange & Teal (Cinematic Viral Look)

# Popular cinematic color grade - orange in highlights, teal in shadows
ffmpeg -i input.mp4 \
  -vf "\
    eq=contrast=1.15:saturation=1.1:brightness=-0.02,\
    colorbalance=rs=0.12:gs=-0.04:bs=-0.15:rm=0.08:gm=-0.02:bm=-0.08:rh=0.08:gh=-0.03:bh=-0.12,\
    curves=all='0/0.02 0.5/0.5 1/0.98',\
    unsharp=5:5:0.6\
  " \
  -c:v libx264 -preset medium -crf 22 \
  output_orange_teal.mp4

3. Vibrant Social Media Look

# Optimized for TikTok/Reels - saturated, sharp, mobile-friendly
ffmpeg -i input.mp4 \
  -vf "\
    eq=saturation=1.25:contrast=1.18:brightness=0.01:gamma=1.05,\
    colorbalance=rs=0.05:bs=-0.05,\
    unsharp=5:5:0.7\
  " \
  -c:v libx264 -preset medium -crf 22 \
  output_vibrant.mp4

4. Moody & Dramatic (Storytelling)

# Lower saturation, higher contrast, lifted blacks
ffmpeg -i input.mp4 \
  -vf "\
    eq=saturation=0.95:contrast=1.25:brightness=-0.03,\
    curves=all='0/0.05 0.5/0.48 1/0.95',\
    colorbalance=bs=0.08:bh=-0.05,\
    unsharp=5:5:0.5\
  " \
  -c:v libx264 -preset medium -crf 22 \
  output_moody.mp4

Using LUTs for Consistent Branding

# Apply a .cube LUT file for professional color grading
ffmpeg -i input.mp4 \
  -vf "lut3d=file=cinematic.cube,unsharp=5:5:0.6" \
  -c:v libx264 -preset medium -crf 22 \
  output_lut.mp4

Popular LUT sources:

CapCut built-in LUTs (export as .cube)
DaVinci Resolve free LUTs
RocketStock free LUTs

Color Grading Best Practices

Test on mobile first: View on phone before posting
Avoid over-saturation: >1.3 saturation looks artificial
Check dark scenes: Compression artifacts most visible in shadows
Platform compression: Colors shift slightly after upload - compensate with +5% saturation
Consistent branding: Use same LUT across all videos for recognition

Text & Caption Parameters for Mobile Readability (2025-2026)

Font Size Guidelines (1080x1920 vertical)

| Content Type | Minimum Size | Recommended Size | Maximum Size | |--------------|--------------|------------------|--------------| | Body text/captions | 48px | 52-60px | 72px | | Titles/hooks | 64px | 72-80px | 120px | | Secondary text | 36px | 40-48px | 56px |

Rule of thumb: For 1080x1920, minimum 48px for readability on all devices.

Safe Zones for Text Placement

┌─────────────────────┐
│   14% TOP MARGIN    │ ← Username, UI elements
├─────────────────────┤
│                     │
│   SAFE TEXT ZONE    │ ← Place all text here
│   (upper 2/3)       │
│                     │
├─────────────────────┤
│                     │
│  35% BOTTOM MARGIN  │ ← Captions, buttons, likes
└─────────────────────┘
    6%         6%
  ← margin  margin →

Best text placement: Upper-middle area (20-60% from top)

FFmpeg Text Overlay Parameters

Optimal Readability Settings

# Maximum mobile readability - white text, thick black outline
ffmpeg -i input.mp4 \
  -vf "drawtext=text='YOUR TEXT':fontsize=56:fontcolor=white:borderw=4:bordercolor=black:x=(w-tw)/2:y=h*0.15" \
  -c:v libx264 -preset medium -crf 22 \
  output_text.mp4

High-Contrast Combinations (Best Performing)

| Text Color | Outline Color | Background | Readability Score | |------------|---------------|------------|-------------------| | White | Black (4px) | Any | 95% | | Yellow | Black (4px) | Dark | 93% | | Black | White (3px) | Light | 92% | | Red | White (4px) | Any | 88% |

Text Animation for Engagement

# Fade-in text (2-second duration)
ffmpeg -i input.mp4 \
  -vf "drawtext=text='STOP SCROLLING':fontsize=72:fontcolor=yellow:borderw=5:bordercolor=black:x=(w-tw)/2:y=h*0.15:alpha='if(lt(t,1),t,1)':enable='between(t,0,2)'" \
  -c:v libx264 -preset medium -crf 22 \
  output_fade_text.mp4

Caption Best Practices (2025-2026)

Research findings:

Captions increase engagement by 80% (TikTok)
94% of Reels watched on mobile with sound off
Maximum 30 characters per line for readability
Maximum 3 lines of text on screen simultaneously
Minimum 2.3 seconds display time for 30-character line

Recommended caption style:

# Auto-caption burn-in (CapCut style)
-vf "subtitles=captions.srt:force_style='\
FontName=Arial Black,\
FontSize=52,\
PrimaryColour=&HFFFFFF,\
OutlineColour=&H000000,\
Outline=4,\
Shadow=0,\
Bold=1,\
Alignment=2,\
MarginV=250'"

Mobile Browser Playback Compatibility

While platform upload specs focus on what TikTok/YouTube/Instagram accept, mobile browser playback has its own requirements. Videos embedded in web apps, PWAs, or mobile browsers must meet stricter codec constraints than native app uploads.

H.264 Profile and Level Requirements

| Profile & Level | Device Support | Use Case | |-----------------|---------------|----------| | Baseline Profile Level 3.0 | All devices since 2010, oldest Android 4.x | Maximum compatibility, lowest quality | | Main Profile Level 3.1 | Android 5+, iPhone 5+, all modern devices | Good balance for older device support | | High Profile Level 4.0 | Android 6+, iPhone 6+, all 2015+ devices | Recommended default for web playback | | High Profile Level 4.1 | Android 7+, iPhone 6s+, all 2016+ devices | Safe maximum for mobile, Blu-ray standard | | High Profile Level 5.1 | Desktop only, some flagship phones | 4K content, NOT safe for general mobile | | High 4:4:4 Predictive | Desktop software decoders only | NEVER use --- fails on all mobile |

Recommendation: Use High Profile Level 4.0 for web-embedded video. It provides 15-25% bitrate savings over Baseline while maintaining near-universal mobile support on devices from 2015 onward.

The Faststart Requirement Explained

The moov atom is MP4's metadata container that tells the player where each frame is located, what codecs are used, and the video's structure. By default, FFmpeg writes it at the end of the file:

Default MP4:  [ftyp] [mdat (video data)] [moov (metadata)]
                                          ^ Player must download entire file
                                            before knowing how to play it

Faststart:    [ftyp] [moov (metadata)] [mdat (video data)]
                     ^ Player reads metadata first, starts playing immediately

On mobile networks (3G/4G/5G), without faststart:

Video appears to hang while the full file downloads
Users on slow connections see a black screen for seconds
Safari may refuse to play the video entirely
Progressive download is impossible

Always use -movflags +faststart for any video that will be played in a browser or streamed over HTTP.

Pixel Format Requirements

Mobile hardware video decoders only support yuv420p (4:2:0 chroma subsampling, 8-bit). Other formats will either:

Fall back to slow software decoding (causing stuttering and battery drain)
Display corrupted colors (green/purple tint)
Fail to play entirely

# Check if a video uses a mobile-safe pixel format
ffprobe -v error -select_streams v:0 -show_entries stream=pix_fmt -of csv=p=0 INPUT

# SAFE:    yuv420p
# UNSAFE:  yuv422p, yuv444p, yuv420p10le (10-bit), gbrp, rgb24

Universal Mobile-Safe FFmpeg Preset

This preset guarantees playback on virtually all mobile browsers from 2015 onward:

# Universal mobile-safe encoding preset
ffmpeg -i input.mp4 \
  -c:v libx264 \
  -profile:v high -level 4.0 \
  -preset medium -crf 23 \
  -pix_fmt yuv420p \
  -c:a aac -profile:a aac_low \
  -b:a 128k -ar 44100 -ac 2 \
  -movflags +faststart \
  -max_muxing_queue_size 1024 \
  output_mobile_safe.mp4

For maximum compatibility (including Android 4.x and old WebViews):

# Maximum compatibility preset (older devices)
ffmpeg -i input.mp4 \
  -c:v libx264 \
  -profile:v main -level 3.1 \
  -preset medium -crf 23 \
  -pix_fmt yuv420p \
  -c:a aac -profile:a aac_low \
  -b:a 96k -ar 44100 -ac 2 \
  -vf "scale='min(1280,iw)':-2" \
  -movflags +faststart \
  output_max_compat.mp4

Mobile Codec Support Matrix

| Feature | iOS Safari | Android Chrome | Samsung Internet | Firefox Android | |---------|-----------|---------------|-----------------|----------------| | H.264 Baseline | All versions | All versions | All versions | All versions | | H.264 Main | All versions | All versions | All versions | All versions | | H.264 High | All versions | 4.4+ | All versions | All versions | | H.264 Level 4.1 | All versions | 5.0+ | All versions | All versions | | HEVC/H.265 | iOS 11+ (hardware) | Chrome 107+ (hardware only) | Varies (hardware) | Not supported | | VP9 | iOS 16.4+ | All versions | All versions | All versions | | AV1 | iPhone 15 Pro+ | Hardware-dependent | Hardware-dependent | Android 10+ | | AAC-LC | All versions | All versions | All versions | All versions | | HE-AAC v2 | All versions | Most versions | Most versions | Partial | | Opus (WebM) | iOS 15+ | All versions | All versions | All versions | | Opus (MP4) | Not supported | Chrome 100+ | Limited | Limited | | yuv420p | Required | Required | Required | Required | | yuv422p/yuv444p | Not supported | Not supported | Not supported | Software only | | 10-bit (yuv420p10le) | iPhone 8+ (HEVC only) | Limited | Limited | Software only | | faststart (moov atom) | Required for streaming | Required for streaming | Required for streaming | Required for streaming | | Autoplay (muted) | Requires playsinline | Allowed | Allowed | Allowed | | Autoplay (unmuted) | Blocked | Blocked | Blocked | Blocked |

Common Mobile Gotchas

HEVC/H.265 is NOT universal: Only iOS Safari and some Android Chrome (with hardware decoder) support it. Firefox Android does not support HEVC at all. Always provide an H.264 fallback.
10-bit color fails on most mobile: Videos encoded with yuv420p10le (common in HDR content) will not play on most mobile browsers. Convert to 8-bit yuv420p for web delivery.
Opus in MP4 containers: While Opus is efficient, it is poorly supported in MP4 containers on mobile. Use AAC-LC for MP4, or use Opus only in WebM containers.
Safari requires playsinline: Without the playsinline attribute in the HTML <video> tag, iOS Safari forces fullscreen playback. This is an HTML attribute, not an encoding issue, but it is the most common "why won't my video play inline on iPhone" complaint.
Audio-only autoplay is blocked: All mobile browsers block autoplay of videos with audible audio. Videos must be muted to autoplay. This cannot be worked around with encoding --- it is a browser policy.

Related Skills

ffmpeg-viral-tiktok - TikTok-specific viral optimization
ffmpeg-viral-shorts - YouTube Shorts optimization
viral-video-hook-templates - 10 proven hook patterns
viral-video-animated-captions - CapCut-style captions

Agent Skills: Viral Video Platform Specifications (2025-2026)

Install this agent skill to your local

Skill Files

CRITICAL GUIDELINES

Windows File Path Requirements

Documentation Guidelines

Viral Video Platform Specifications (2025-2026)

Quick Reference Table

TikTok Specifications

Technical Requirements (2025-2026)

Optimal Encoding Parameters (2025-2026)

FFmpeg Preset (Updated 2025-2026)

Two-Pass Encoding for Precise Bitrate Control

Algorithm Insights (2025-2026)

YouTube Shorts Specifications

Technical Requirements (2025-2026)

Optimal Encoding Parameters (2025-2026)

FFmpeg Preset - H.264 (Updated 2025-2026)

Two-Pass Encoding for Optimal Quality

FFmpeg Preset (VP9 - Higher Quality)

Algorithm Insights (2025-2026)

Instagram Reels Specifications

Technical Requirements (2025-2026)

Optimal Encoding Parameters (2025-2026)

Safe Zones (2025-2026)

FFmpeg Preset (Updated 2025-2026)

Bitrate-Controlled Encoding

Algorithm Insights (2025-2026)

Facebook Reels Specifications

Technical Requirements (2025-2026)

Optimal Encoding Parameters (2025-2026)

FFmpeg Preset (Updated 2025-2026)

High-Quality Preset (Bitrate-Controlled)

Algorithm Insights (2025-2026)

Snapchat Spotlight Specifications

Technical Requirements

FFmpeg Preset

Twitter/X Video Specifications

Technical Requirements

FFmpeg Preset

Multi-Platform Export Script

File Size Optimization

Calculate Target Bitrate for File Size

Two-Pass Encoding for Exact Size

Platform Comparison: Algorithm Factors

Verification Commands

Codec Comparison for Short-Form Video (2025-2026)

H.264 vs H.265 vs AV1 Decision Matrix

Platform Codec Recommendations

Color Grading for Viral Appeal (2025-2026)

Mobile-Optimized Color Parameters

Viral Color Grading Presets

1. Bold & Eye-Popping (Maximum Engagement)

2. Orange & Teal (Cinematic Viral Look)

3. Vibrant Social Media Look

4. Moody & Dramatic (Storytelling)

Using LUTs for Consistent Branding

Color Grading Best Practices

Text & Caption Parameters for Mobile Readability (2025-2026)

Font Size Guidelines (1080x1920 vertical)

Safe Zones for Text Placement

FFmpeg Text Overlay Parameters

Optimal Readability Settings

High-Contrast Combinations (Best Performing)

Text Animation for Engagement

Caption Best Practices (2025-2026)

Mobile Browser Playback Compatibility

H.264 Profile and Level Requirements

The Faststart Requirement Explained

Pixel Format Requirements

Universal Mobile-Safe FFmpeg Preset

Mobile Codec Support Matrix

Common Mobile Gotchas

Related Skills