[Mp4-tech] Encoding information in MP4 file

[tech list]

As you guessed, ftyp cannot be used. There are encoder specific fields
somewhere in the media header, though I dont remember exactly where.
You could look up the specs.
On 9/21/06, Adam Potolsky <adamp ipinfusion.com> wrote:
>
>  Good day,
>
>
>
> In continuing work on MP4 file, I have found that there is more data that
> I need to gather form the MP4 files and I am having difficulty finding this
> information. In particular, I am hunting down a definitive way to know the
> specific encoding used for the video and audio channel. In the case of an
> MPEG4-P2 track, I want to know which Profile was used. (Simple Profile,
> Advance Simple Profile, etc…) I have looked at the 'stsd' atom and it looks
> like the "compressor" name can be set to 0 for size so this seems an
> unreliable source for this data. In the 'ftyp' atom, there appears to be the
> data I might be able to use, however, I'm not sure of its reliability in
> terms of what I want.
>
>
>
> For example:
>
>
>
> ... ftyp3gp6....
>
> 3gp63g2aisomavc1
>
> ..&.moov...lmvhd
>
> …
>
> …
>
> .....stbl....sts
>
> d............avc
>
> …
>
> ..*avcC.B...!..'
>
> B....m.... ...Dx
>
> 7474  .....(....
>
>
>
> Uses H.264 encoding, but the 'ftyp' doesn't state that explicitly.
>
>
>
> Is there a way to tell the specific encoding box data?
>
> If so, how, and If not, can anyone recommend another way to find this
> information out?
>
>
>
> Thank you in advance for you assistance,
>
> Adam Potolsky
>
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