[FFmpeg-user] DNxHD / MOV: what is the extra data in stsd?

[Baptiste Coudurier]

Hi Thomas,

On 05/30/2011 02:03 PM, Thomas Worth wrote:
> I noticed that encoding a DNxHD encoded MOV with FFmpeg results in some
> extra data in the stsd atom for the video track. This data isn't there after
> encoding to other codecs, say Apple Animation/qtrle for example. At its most
> basic structure, stsd is 102 bytes, but with DNxHD material is is I think
> 275 bytes. Furthermore, this data is apparently needed to render the video
> correctly, because if I truncate stsd to 102, the resulting video is black
> in the QuickTime player (it still plays in VLC, though).
> 
> This is some of what I'm seeing (as text):
> 
> ACLRACLR0001
> APRGAPRG0001
> ARESARES0001
> 
> What is this data and what is referencing it? I have some additional stsd
> parameters I need to insert, but I don't know if putting stuff in before the
> "DNxHD extra data" (what we'll call it) will confuse whatever is looking for
> this extra data.
> 
> Baptiste?

It's extradata not completely deciphered yet, these parameters are
required for decoding by the avid decoders for some reason.
Some colorspace information, resolution information.

-- 
Baptiste COUDURIER
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