Format Conversion

Convert videos and audio between different formats using yt-dlp

Overview

yt-dlp can convert downloaded media to different formats using ffmpeg. This includes remuxing (changing container without re-encoding) and transcoding (re-encoding to a different codec).

Remuxing is faster and maintains quality, while transcoding allows codec changes but may reduce quality.

Remuxing Videos

Remux changes the container format without re-encoding the video/audio streams:

# Remux to MP4 if needed
yt-dlp --remux-video mp4 URL

# Remux to MKV
yt-dlp --remux-video mkv URL

# Remux to WebM
yt-dlp --remux-video webm URL

Supported container formats

• Video: mp4, mkv, webm, flv, avi, mov, gif
• Audio: m4a, aac, mp3, opus, ogg, flac, wav, alac, mka, aiff

Conditional Remuxing

Use rules to remux specific formats:

Single Rule

# Remux AAC files to M4A
yt-dlp --remux-video "aac>m4a" URL

# Multiple conversion rules
yt-dlp --remux-video "aac>m4a/mov>mp4/mkv" URL

# This will:
# - Remux AAC to M4A
# - Remux MOV to MP4  
# - Remux everything else to MKV
yt-dlp --remux-video "aac>m4a/mov>mp4/mkv" URL

Re-encoding Videos

Re-encoding reduces quality and takes much longer than remuxing. Use only when necessary.

Transcode videos to different codecs:

# Re-encode to MP4 (if necessary)
yt-dlp --recode-video mp4 URL

# Re-encode to WebM
yt-dlp --recode-video webm URL

# Conditional re-encoding with same syntax as remux
yt-dlp --recode-video "avi>mp4/flv>mp4/mp4" URL

Audio Format Conversion

Extract and convert audio

1. Basic extraction

   # Extract audio in best format
   yt-dlp -x URL
   
2. Convert to specific format

   # Convert to MP3
   yt-dlp -x --audio-format mp3 URL
   
   # Convert to AAC
   yt-dlp -x --audio-format aac URL
   
   # Convert to FLAC (lossless)
   yt-dlp -x --audio-format flac URL
   
3. Set audio quality

   # VBR quality (0=best, 10=worst)
   yt-dlp -x --audio-format mp3 --audio-quality 0 URL
   
   # Specific bitrate
   yt-dlp -x --audio-format mp3 --audio-quality 320K URL
   

Conditional audio conversion

# Convert opus to mp3, keep others as best
yt-dlp -x --audio-format "opus>mp3/best" URL

Format Selection with Conversion

Combine format selection with conversion for precise control:

Best Quality MP4

# Download best video+audio and merge to MP4
yt-dlp -f "bv*+ba" --merge-output-format mp4 URL

# Best h264 video + AAC audio in MP4
yt-dlp -f "bv*[vcodec^=avc]+ba[acodec^=mp4a]" \
  --merge-output-format mp4 URL

# Ensure final output is MP4
yt-dlp -f "bv*+ba/b" \
  --merge-output-format mp4 \
  --remux-video mp4 URL

Preset Format Conversions

yt-dlp includes useful presets:

MP4 Preset

# Equivalent to:
# --merge-output-format mp4 --remux-video mp4
# -S vcodec:h264,lang,quality,res,fps,hdr:12,acodec:aac
yt-dlp -t mp4 URL

This preset:

• Sets output to MP4 container
• Prefers H.264 video codec
• Prefers AAC audio codec
• Optimizes for compatibility

MKV Preset

# Equivalent to:
# --merge-output-format mkv --remux-video mkv
yt-dlp -t mkv URL

Converting Existing Files

Convert already downloaded videos:

1. Download metadata

   # First download with metadata
   yt-dlp --write-info-json URL
   
2. Re-process the file

   # Process using saved info.json
   yt-dlp --load-info-json video.info.json \
     --remux-video mp4
   

Subtitle Format Conversion

Convert subtitle formats:

# Convert subtitles to SRT
yt-dlp --write-subs --convert-subs srt URL

# Convert to VTT
yt-dlp --write-subs --convert-subs vtt URL

# Convert to ASS
yt-dlp --write-subs --convert-subs ass URL

# Disable conversion (keep original)
yt-dlp --write-subs --convert-subs none URL

Thumbnail Format Conversion

Convert thumbnail images:

# Convert thumbnails to JPG
yt-dlp --write-thumbnail --convert-thumbnails jpg URL

# Convert to PNG
yt-dlp --write-thumbnail --convert-thumbnails png URL

# Convert to WebP
yt-dlp --write-thumbnail --convert-thumbnails webp URL

# Multiple rules (similar to remux-video)
yt-dlp --write-thumbnail --convert-thumbnails "webp>jpg/png" URL

Advanced Conversion Scenarios

Encode for specific devices

Apple Devices

# H.264 + AAC in MP4 (maximum compatibility)
yt-dlp -f "bv*[vcodec^=avc]+ba[acodec^=mp4a]" \
  --merge-output-format mp4 \
  --ppa "ffmpeg:-c:v libx264 -c:a aac" \
  URL

# Modern codec support
yt-dlp --merge-output-format mp4 \
  --remux-video mp4 \
  -S "vcodec:h264,acodec:aac" \
  URL

# WebM for web playback
yt-dlp -f "bv*[ext=webm]+ba[ext=webm]" \
  --merge-output-format webm \
  URL

Compress video

Re-encoding will reduce quality. Always keep original files when compressing.

# Download and compress
yt-dlp URL \
  --recode-video mp4 \
  --ppa "ffmpeg:-c:v libx264 -crf 23 -c:a aac -b:a 128k"

Convert with custom ffmpeg options

# Custom video encoding
yt-dlp URL \
  --recode-video mp4 \
  --ppa "ffmpeg:-c:v libx264 -preset slow -crf 18"

# Custom audio encoding  
yt-dlp -x --audio-format mp3 \
  --ppa "ffmpeg:-q:a 0" \
  URL

Merge Multiple Streams

Merge video and audio while converting:

# Download best video and audio, merge to MP4
yt-dlp -f "bv+ba" \
  --merge-output-format mp4 \
  URL

# Merge specific formats
yt-dlp -f "137+140" \
  --merge-output-format mp4 \
  URL

Merge with multiple audio tracks

# Enable audio multistreams and merge
yt-dlp -f "bv*+ba+ba.2" \
  --audio-multistreams \
  --merge-output-format mkv \
  URL

Fixup Options

Automatically fix common format issues:

# Auto-detect and fix file issues
yt-dlp --fixup detect_or_warn URL

# Force fixing
yt-dlp --fixup force URL

# Never fix
yt-dlp --fixup never URL

Common Conversion Workflows

Maximum compatibility

# MP4 with H.264 and AAC (plays everywhere)
yt-dlp -t mp4 -S "vcodec:h264,acodec:aac" URL

Archival quality

# Best quality in MKV container
yt-dlp -f "bv*+ba" --merge-output-format mkv \
  --embed-metadata --embed-subs --embed-thumbnail \
  URL

Space-efficient

# Good quality, smaller file size
yt-dlp --recode-video mp4 \
  --ppa "ffmpeg:-c:v libx264 -crf 23 -c:a aac -b:a 128k" \
  URL

Audio for music players

# High quality M4A with metadata
yt-dlp -x --audio-format m4a --audio-quality 256K \
  --embed-metadata --embed-thumbnail \
  URL

Troubleshooting

Conversion fails

# Check ffmpeg version
ffmpeg -version

# Try remuxing instead of re-encoding
yt-dlp --remux-video mp4 URL

# Check if format supports the codec
yt-dlp --list-formats URL

Container doesn’t support codec

# Use compatible container (MKV supports almost everything)
yt-dlp --merge-output-format mkv URL

# Or re-encode to compatible codec
yt-dlp --recode-video mp4 URL

Quality loss

Always prefer remuxing over re-encoding when you only need to change the container format.

# Use remux instead of recode
yt-dlp --remux-video mp4 URL  # Good
yt-dlp --recode-video mp4 URL  # Avoid if possible

Next Steps

Post-Processing

Learn about all post-processing options

Audio Extraction

Detailed audio extraction guide

Format Selection

Advanced format selection reference

Post-Processor Arguments

ffmpeg and post-processor arguments