5 ms·

Since most of us associate mp4 with moving images, what exactly is usually wrapped in the mp4 container, and is there a good introduction on the topic available

Since most of us associate mp4 with moving images, what exactly is usually wrapped in the mp4 container, and is there a good introduction on the topic available?

nimish 4y ago
Audio and video. Wikipedia has a terse but comprehensive overview. It's comparable to Matroska (MKV). It's nearly identical to apple's QuickTime format: https://developer.apple.com/library/archive/documentation/QuickTime/QTFF/QTFFChap1/qtff1.html https://developer.apple.com/library/archive/documentation/Qu...
- CharlesW 4y ago
  > Audio and video. And images! The same container format¹ is used by AVIF. ¹ ISOBMFF (ISO base media file format), which is ISO/IEC 14496-12 (a.k.a. MPEG-4 Part 12).
pjc50 4y ago
Moving images. Generally in the form of a video stream (usually h264, but it can be anything), one or more audio stream (AAC or MP3), and a timestamp index that keeps them aligned and makes it easier to seek. It's not especially easy to find good documentation; people generally don't write software to touch it directly, either they use the OS media library or ffmpeg.
wwader 4y ago
If you want to go deep ISO-14496-12 is probably what your looking for. You can either pay ISO to read it or hypothetically you can google for "filetype:pdf ISO-14496-12". For how things actually work in practice https://github.com/FFmpeg/FFmpeg/blob/master/libavformat/mov.c https://github.com/FFmpeg/FFmpeg/blob/master/libavformat/mov... is a good resource.
- Const-me 4y ago
  > For how things actually work in practice Another version of the demuxer, way simpler: https://github.com/Const-me/Vrmac/blob/master/VrmacVideo/Containers/MP4/Mp4Reader.cs https://github.com/Const-me/Vrmac/blob/master/VrmacVideo/Con... A complete mpeg4 media file, with enough features to play the content with hardware decoding: https://github.com/Const-me/Vrmac/blob/master/VrmacVideo/Containers/MP4/Mp4File.cs https://github.com/Const-me/Vrmac/blob/master/VrmacVideo/Con...

Since most of us associate mp4 with moving images, what exactly is usually wrapped in the mp4 container, and is there a good introduction on the topic available?

nimish 4y ago

Audio and video. Wikipedia has a terse but comprehensive overview. It's comparable to Matroska (MKV). It's nearly identical to apple's QuickTime format: https://developer.apple.com/library/archive/documentation/QuickTime/QTFF/QTFFChap1/qtff1.html https://developer.apple.com/library/archive/documentation/Qu...

CharlesW 4y ago
> Audio and video. And images! The same container format¹ is used by AVIF. ¹ ISOBMFF (ISO base media file format), which is ISO/IEC 14496-12 (a.k.a. MPEG-4 Part 12).

pjc50 4y ago

Moving images. Generally in the form of a video stream (usually h264, but it can be anything), one or more audio stream (AAC or MP3), and a timestamp index that keeps them aligned and makes it easier to seek. It's not especially easy to find good documentation; people generally don't write software to touch it directly, either they use the OS media library or ffmpeg.

wwader 4y ago

If you want to go deep ISO-14496-12 is probably what your looking for. You can either pay ISO to read it or hypothetically you can google for "filetype:pdf ISO-14496-12". For how things actually work in practice https://github.com/FFmpeg/FFmpeg/blob/master/libavformat/mov.c https://github.com/FFmpeg/FFmpeg/blob/master/libavformat/mov... is a good resource.

Const-me 4y ago
> For how things actually work in practice Another version of the demuxer, way simpler: https://github.com/Const-me/Vrmac/blob/master/VrmacVideo/Containers/MP4/Mp4Reader.cs https://github.com/Const-me/Vrmac/blob/master/VrmacVideo/Con... A complete mpeg4 media file, with enough features to play the content with hardware decoding: https://github.com/Const-me/Vrmac/blob/master/VrmacVideo/Containers/MP4/Mp4File.cs https://github.com/Const-me/Vrmac/blob/master/VrmacVideo/Con...