[FFmpeg-user] What are the the data and attachment stream type?

[Dave Rice]

> On Jun 29, 2015, at 6:12 AM, Guofeng Zhang <guofengzh at gmail.com> wrote:
> 
> Hi,
> 
> The book "FFmpeg Basic" described that FFmpeg recognizes 5 stream types:
> audio (a), attachment (t), data (d), subtitle (s) and video (v).
> 
> I do not understand what the data and attachment type specified and what
> they are used for.
> 
> Is there any introduction about data and attachment stream type on the
> internet?

Attachments could be liner notes, related images, metadata files, fonts, etc. Here are some samples:
http://samples.ffmpeg.org/Matroska/size_change/azumi.mkv
http://samples.ffmpeg.org/Matroska/120fps-mkv/[KTKJ][stratos4_advance][01][big5][E72C0C1D].mkv <http://samples.ffmpeg.org/Matroska/120fps-mkv/%5BKTKJ%5D%5Bstratos4_advance%5D%5B01%5D%5Bbig5%5D%5BE72C0C1D%5D.mkv>
http://samples.ffmpeg.org/Matroska/aac-sbr-ffaac-slow.mkv <http://samples.ffmpeg.org/Matroska/aac-sbr-ffaac-slow.mkv>
http://samples.ffmpeg.org/Matroska/haruhi.mkv <http://samples.ffmpeg.org/Matroska/haruhi.mkv>
http://samples.ffmpeg.org/Matroska/subtitles/embedded_ass/embedded_ass_problems.mkv <http://samples.ffmpeg.org/Matroska/subtitles/embedded_ass/embedded_ass_problems.mkv>

Data tracks would be for things like timecode, navigation items, cmml, streaming tracks. See samples:
http://samples.ffmpeg.org/A-codecs/AAC/Bandit.mp4 <http://samples.ffmpeg.org/A-codecs/AAC/Bandit.mp4>
http://samples.ffmpeg.org/A-codecs/AAC/ct_nero-heaac.mp4 <http://samples.ffmpeg.org/A-codecs/AAC/ct_nero-heaac.mp4>
http://samples.ffmpeg.org/A-codecs/AC3/a52dec-streams/zorro <http://samples.ffmpeg.org/A-codecs/AC3/a52dec-streams/zorro>

Best Regards,
Dave Rice