[foms] Proposal: adaptive streaming using open codecs

Steve Lhomme slhomme at matroska.org
Sat Nov 20 02:27:28 PST 2010

On Fri, Nov 19, 2010 at 12:56 PM, Pierre-Yves KEREMBELLEC
<pierre-yves.kerembellec at dailymotion.com> wrote:
>  In most formats there are file/codec headers that you don't want to repeat
>  in every chunk (seems to be true for mp4 and WebM).
> Agreed for MP4, but for "streamable" containers (like MPEG-TS of FLV), the
> overhead is really minimal for most codecs.
> And it would probably ease implementation (and debugging) this way.

Does anyone know of any tool that can take a MP4 and split it in
"adaptative friendly" chuncks ? I'd like to make a comparison between
MP4 and Matroska on that.

As I said earlier, Matroska/WebM chuncks don't need the Cues/Meta Seek
elements in the file to be playable, nor even actual sizes for
surrounding elements, making it easy to create on the fly with minimal
caching (if any at all).

Anyway, just preaching for my own, as I know Adaptative Streaming will
not just be WebM but very likely coexist with MP4 variants.

> [Steve]
> I agree, even though that may make Vorbis a little less competitive (8 KB
> codec initialization).
> 8K ?! What exactly is being passed in 8K for an audio codec initialization
> sequence ?
> (by comparison, the initialization sequence for AAC is only 2 bytes)

In fact in my WebM sample files it's more between 3 KB and 7 KB. Most
of them being around 3 KB. It corresponds to a codebook init. I think
Monty could explain that better than me.


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