# Encoding Filters Pack - Muxers Reference

This document provides comprehensive information about all container formats (muxers) supported by the DirectShow Encoding Filters Pack. Muxers combine video and audio streams into container files for storage and streaming.

MPEG-4 Part 14 (MP4) is the most widely used container format for video distribution.

File Extensions: .mp4, .m4v, .m4a (audio only)

MIME Type: video/mp4, audio/mp4

• H.264/AVC ✓ (Primary)
• H.265/HEVC ✓
• MPEG-4 Part 2 ✓
• MPEG-2 ✗ (use MPEG-TS instead)
• VP8/VP9 ✗ (use WebM instead)

• AAC ✓ (Primary)
• MP3 ✓
• Opus ✗
• Vorbis ✗
• FLAC ✓
• PCM ✓

Streaming Support:

• Progressive Download: ✓ (with proper moov atom placement)
• Adaptive Streaming: ✓ (DASH, HLS with fragmented MP4)
• Live Streaming: ✓ (fragmented MP4)

Metadata Support:

• Basic Tags: Title, artist, album, year
• Cover Art: ✓
• Chapters: ✓
• Subtitles: ✓ (VTT, SRT, various text formats)

Technical Features:

• Multiple Audio Tracks: ✓
• Multiple Subtitle Tracks: ✓
• Fast Start: ✓ (moov atom at beginning)
• Fragmented MP4: ✓ (for streaming)

For Progressive Download (Web):

- Place moov atom at beginning (fast start)
- Use H.264 Baseline/Main profile
- AAC-LC audio
- Keyframe interval: 2-4 seconds

For Local Playback:

- H.264 High profile or H.265
- AAC-LC or HE-AAC
- Any keyframe interval

For Streaming (DASH/HLS):

- Fragmented MP4
- H.264 Main/High profile
- AAC-LC audio
- Short fragments (2-6 seconds)

Issue: Video not seekable on web

• Solution: Enable fast start (moov at beginning)

Issue: Audio sync problems

• Solution: Use constant frame rate, check audio sample rate

Matroska is an open-standard, feature-rich container format.

File Extensions: .mkv (video), .mka (audio), .mks (subtitles)

MIME Type: video/x-matroska, audio/x-matroska

• H.264/AVC ✓
• H.265/HEVC ✓
• VP8 ✓
• VP9 ✓
• MPEG-4 Part 2 ✓
• MPEG-2 ✓
• AV1 ✓

• AAC ✓
• MP3 ✓
• Opus ✓
• Vorbis ✓
• FLAC ✓
• DTS ✓
• AC-3 ✓
• PCM ✓

Advanced Features:

• Multiple Video Tracks: ✓
• Multiple Audio Tracks: ✓ (unlimited)
• Multiple Subtitle Tracks: ✓ (unlimited)
• Attachments: ✓ (fonts, cover art)
• Chapters: ✓ (with nesting)
• Tags/Metadata: ✓ (extensive)
• Segmenting: ✓ (linked segments)

Technical Capabilities:

• Variable Frame Rate: ✓
• Lossless Audio: ✓
• 3D/Stereoscopic: ✓
• HDR Metadata: ✓

For Archival:

- Use FLAC or PCM for lossless audio
- Include all audio/subtitle tracks
- Add chapter markers
- Include metadata tags

For Distribution:

- H.264/H.265 video
- AAC audio (most compatible)
- Embedded soft subtitles
- Reasonable file size

For Streaming:

- Not ideal for streaming
- Consider MP4 or WebM instead
- If used: disable complex features

Issue: Seeking is slow

• Solution: Enable cues (index) during muxing

Issue: Playback stuttering with high-quality audio

• Solution: Check decoder performance, consider AAC instead of lossless

WebM is an open, royalty-free format designed for web use.

File Extensions: .webm

MIME Type: video/webm, audio/webm

• VP8 ✓ (WebM 1.0)
• VP9 ✓ (WebM 2.0)
• AV1 ✓ (experimental)
• H.264 ✗
• H.265 ✗

• Vorbis ✓ (Primary)
• Opus ✓ (Recommended)
• AAC ✗
• MP3 ✗

Web Optimized:

• HTML5 Video: ✓ (native browser support)
• Streaming: ✓
• Adaptive Streaming: ✓ (DASH)
• Low Latency: ✓

Metadata Support:

• Basic Tags: ✓
• Chapters: ✓
• Subtitles: ✓ (WebVTT)

For YouTube/Web:

- VP9 video codec
- Opus audio codec (96-160 kbps)
- Keyframe interval: 2-4 seconds
- Two-pass encoding for best quality

For Live Streaming:

- VP8 for better encoder performance
- Opus audio (low latency mode)
- CBR bitrate
- Short GOP

For High Quality:

- VP9 with high bitrate
- Opus 128-256 kbps
- Two-pass encoding
- Quality-based rate control

Issue: Safari won't play WebM

• Solution: Provide MP4 fallback with H.264

Issue: Encoding too slow

• Solution: Use VP8 instead of VP9, or hardware-accelerated VP9 if available

MPEG Transport Stream is designed for broadcast and streaming, especially where error resilience is important.

File Extensions: .ts, .mts, .m2ts

MIME Type: video/mp2t

• H.264/AVC ✓
• H.265/HEVC ✓
• MPEG-2 ✓
• VP8/VP9 ✗

• AAC ✓
• MP3 ✓
• AC-3 ✓
• PCM ✓

Broadcast Features:

• Error Resilience: ✓ (built-in error recovery)
• Time-shifting: ✓
• Program Multiplexing: ✓ (multiple programs in one stream)
• Encryption: ✓ (conditional access)

Streaming Features:

• HLS Streaming: ✓ (Apple HTTP Live Streaming)
• DVB Broadcasting: ✓
• IPTV: ✓

For HLS Streaming:

- H.264 video
- AAC audio
- Segment duration: 6-10 seconds
- CBR encoding
- Closed GOP

For Broadcasting:

- MPEG-2 or H.264
- AC-3 or AAC audio
- Constant bitrate
- Fixed packet size (188 bytes)

Legacy format formerly used for web video (YouTube, Flash players).

File Extensions: .flv, .f4v

MIME Type: video/x-flv

Status: ⚠️ Deprecated - Use MP4 or WebM instead

• H.264 ✓
• VP6 ✓ (legacy)
• Sorenson Spark ✓ (legacy)

• AAC ✓
• MP3 ✓
• Speex ✓

• Streaming: ✓ (RTMP)
• Metadata: Basic (onMetaData)
• Cue Points: ✓

Not Recommended: Flash Player end-of-life (2020) makes FLV obsolete

Open-source container primarily for Vorbis audio.

File Extensions: .ogg, .oga (audio), .ogv (video)

MIME Type: audio/ogg, video/ogg

• Theora ✓ (legacy quality)
• VP8 ✗ (use WebM)

• Vorbis ✓ (Primary)
• Opus ✓
• FLAC ✓
• Speex ✓

• Streaming: ✓
• Chaining: ✓ (multiple files in sequence)
• Metadata: ✓ (Vorbis comments)

For Audio:

- Vorbis or Opus codec
- Quality-based encoding
- Vorbis comments for metadata

For Video:

- Not recommended
- Use WebM (VP8/VP9) instead

Legacy Microsoft container format.

File Extensions: .avi

MIME Type: video/x-msvideo

Status: ⚠️ Legacy - Use MP4 or MKV for new projects

• H.264 ✓ (limited support)
• MPEG-4 Part 2 ✓
• MPEG-2 ✓
• Various legacy codecs ✓

• MP3 ✓
• PCM ✓
• AC-3 ✓
• AAC Limited

• Max File Size: 2 GB (without OpenDML)
• Limited Metadata: Very basic
• No Streaming: Not designed for streaming
• No Chapters: Not supported

• Legacy system compatibility
• Capture from old hardware
• Specific software requirements

Recommendation: Use MP4 or MKV for new projects

Uncompressed audio container.

File Extensions: .wav

MIME Type: audio/wav, audio/x-wav

• Lossless: ✓ (PCM)
• Compressed: ✓ (MP3, AAC in WAV wrapper)
• Metadata: Limited (RIFF tags)

• PCM 44.1 kHz 16-bit: CD quality
• PCM 48 kHz 24-bit: Professional audio
• PCM 96 kHz 24-bit: High-resolution audio

For Audio Production:

- 48 kHz, 24-bit PCM
- Mono or stereo
- Avoid compression

For Distribution:

- Use FLAC or AAC instead
- WAV files are large

Primary: MP4 (H.264 + AAC)

• Reason: Universal compatibility
• Fallback: WebM (VP9 + Opus) for modern browsers

Primary: MKV (H.265 + FLAC)

• Reason: Feature-rich, lossless audio support
• Alternative: MP4 (H.265 + AAC) for better compatibility

Primary: MPEG-TS (H.264 + AAC)

• Reason: Error resilience, industry standard
• Alternative: MPEG-TS (MPEG-2 + AC-3) for legacy systems

HLS: MPEG-TS segments (H.264 + AAC) DASH: Fragmented MP4 (H.264 + AAC) WebRTC: Opus audio, VP8/H.264 video

High Quality: FLAC (.flac) or MP3 VBR (.mp3) Streaming: AAC in MP4 (.m4a) or Opus in WebM Voice: Opus in OGG or Speex

ftyp (file type)
moov (metadata - place at beginning for fast start)
  ├── mvhd (movie header)
  ├── trak (video track)
  ├── trak (audio track)
  └── udta (user data/metadata)
mdat (media data)

ftyp
moov
  └── mvex (movie extends)
moof (movie fragment)
  └── traf (track fragment)
mdat (fragment data)
[repeat moof/mdat for each fragment]

EBML Header
Segment
  ├── SeekHead (index)
  ├── Info (segment information)
  ├── Tracks (track definitions)
  ├── Chapters (optional)
  ├── Attachments (optional)
  ├── Tags (metadata)
  └── Cluster (media data)

• Encoding Filters Pack Overview
• Codecs Reference
• Code Examples
• NVENC Interface Reference