> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/yt-dlp/yt-dlp/llms.txt
> Use this file to discover all available pages before exploring further.

# 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).

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

## Remuxing Videos

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

```bash theme={null}
# 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:

<CodeGroup>
  ```bash Single Rule theme={null}
  # Remux AAC files to M4A
  yt-dlp --remux-video "aac>m4a" URL
  ```

  ```bash Multiple Rules theme={null}
  # Multiple conversion rules
  yt-dlp --remux-video "aac>m4a/mov>mp4/mkv" URL
  ```

  ```bash Chain Rules theme={null}
  # 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
  ```
</CodeGroup>

## Re-encoding Videos

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

Transcode videos to different codecs:

```bash theme={null}
# 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

<Steps>
  <Step title="Basic extraction">
    ```bash theme={null}
    # Extract audio in best format
    yt-dlp -x URL
    ```
  </Step>

  <Step title="Convert to specific format">
    ```bash theme={null}
    # 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
    ```
  </Step>

  <Step title="Set audio quality">
    ```bash theme={null}
    # 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
    ```
  </Step>
</Steps>

### Conditional audio conversion

```bash theme={null}
# 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:

<CodeGroup>
  ```bash Best Quality MP4 theme={null}
  # Download best video+audio and merge to MP4
  yt-dlp -f "bv*+ba" --merge-output-format mp4 URL
  ```

  ```bash Specific Codecs theme={null}
  # Best h264 video + AAC audio in MP4
  yt-dlp -f "bv*[vcodec^=avc]+ba[acodec^=mp4a]" \
    --merge-output-format mp4 URL
  ```

  ```bash With Remux theme={null}
  # Ensure final output is MP4
  yt-dlp -f "bv*+ba/b" \
    --merge-output-format mp4 \
    --remux-video mp4 URL
  ```
</CodeGroup>

## Preset Format Conversions

yt-dlp includes useful presets:

### MP4 Preset

```bash theme={null}
# 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

```bash theme={null}
# Equivalent to:
# --merge-output-format mkv --remux-video mkv
yt-dlp -t mkv URL
```

## Converting Existing Files

Convert already downloaded videos:

<Steps>
  <Step title="Download metadata">
    ```bash theme={null}
    # First download with metadata
    yt-dlp --write-info-json URL
    ```
  </Step>

  <Step title="Re-process the file">
    ```bash theme={null}
    # Process using saved info.json
    yt-dlp --load-info-json video.info.json \
      --remux-video mp4
    ```
  </Step>
</Steps>

## Subtitle Format Conversion

Convert subtitle formats:

```bash theme={null}
# 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:

```bash theme={null}
# 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

<CodeGroup>
  ```bash Apple Devices theme={null}
  # 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
  ```

  ```bash Android Devices theme={null}
  # Modern codec support
  yt-dlp --merge-output-format mp4 \
    --remux-video mp4 \
    -S "vcodec:h264,acodec:aac" \
    URL
  ```

  ```bash Web Streaming theme={null}
  # WebM for web playback
  yt-dlp -f "bv*[ext=webm]+ba[ext=webm]" \
    --merge-output-format webm \
    URL
  ```
</CodeGroup>

### Compress video

<Warning>
  Re-encoding will reduce quality. Always keep original files when compressing.
</Warning>

```bash theme={null}
# 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

```bash theme={null}
# 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:

```bash theme={null}
# 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

```bash theme={null}
# 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:

```bash theme={null}
# 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

```bash theme={null}
# MP4 with H.264 and AAC (plays everywhere)
yt-dlp -t mp4 -S "vcodec:h264,acodec:aac" URL
```

### Archival quality

```bash theme={null}
# Best quality in MKV container
yt-dlp -f "bv*+ba" --merge-output-format mkv \
  --embed-metadata --embed-subs --embed-thumbnail \
  URL
```

### Space-efficient

```bash theme={null}
# 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

```bash theme={null}
# High quality M4A with metadata
yt-dlp -x --audio-format m4a --audio-quality 256K \
  --embed-metadata --embed-thumbnail \
  URL
```

## Troubleshooting

### Conversion fails

```bash theme={null}
# 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

```bash theme={null}
# 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

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

```bash theme={null}
# Use remux instead of recode
yt-dlp --remux-video mp4 URL  # Good
yt-dlp --recode-video mp4 URL  # Avoid if possible
```

## Next Steps

<CardGroup cols={2}>
  <Card title="Post-Processing" icon="gears" href="/guides/post-processing">
    Learn about all post-processing options
  </Card>

  <Card title="Audio Extraction" icon="music" href="/guides/audio-extraction">
    Detailed audio extraction guide
  </Card>

  <Card title="Format Selection" icon="sliders" href="/core-concepts/format-selection">
    Advanced format selection reference
  </Card>

  <Card title="Post-Processor Arguments" icon="terminal" href="/cli/post-processing-options">
    ffmpeg and post-processor arguments
  </Card>
</CardGroup>