viral-video-platform-specs

name

viral-video-platform-specs

description

Complete platform upload specifications for viral video creation across TikTok, YouTube Shorts, Instagram Reels, Facebook Reels, Snapchat Spotlight, and Twitter/X. PROACTIVELY activate for: (1) Platform-specific video encoding, (2) Upload requirements lookup, (3) Multi-platform export, (4) File size optimization, (5) Aspect ratio conversion, (6) Duration limits, (7) Audio requirements, (8) Caption/subtitle specs, (9) Thumbnail requirements, (10) Quality vs compatibility trade-offs. Provides: Comprehensive spec tables, FFmpeg presets per platform, optimal encoding settings, file size calculators, batch export workflows, and 2025-2026 platform-specific algorithm insights.

CRITICAL GUIDELINES

Windows File Path Requirements

MANDATORY: Always Use Backslashes on Windows for File Paths

When using Edit or Write tools on Windows, you MUST use backslashes (\) in file paths, NOT forward slashes (/).

Documentation Guidelines

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

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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

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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%+

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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

1. Test on mobile first: View on phone before posting
2. Avoid over-saturation: >1.3 saturation looks artificial
3. Check dark scenes: Compression artifacts most visible in shadows
4. Platform compression: Colors shift slightly after upload - compensate with +5% saturation
5. 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

Common Mobile Gotchas

1. 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.

2. 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.

3. 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.

4. 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.

5. 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.

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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