[FFmpeg-devel] parser for the nellymoser decoder
Sun Oct 7 16:10:21 CEST 2007
Michael Niedermayer wrote:
> On Sat, Oct 06, 2007 at 11:26:47PM +0200, Benjamin Larsson wrote:
>> Hi, do I need to code a parser for the nellymoser codec when the audio
>> tags only contain 1,2 or 4 64byte frames ? There is no header to find
>> the only thing to use is the block_size.
> well, why are 1,2 or 4 frames concatenated?
> is it because of some requirement f the container? or is it arbitrary
> and would any packing work if it where muxed?
> would a (flv?) muxer work if it received only 4 frame packs? would it work
> if it receive only 1 frames?
> if these blocks ever need to be split than they definitly need to be split
> in the demuxer or parser
> can this packing change within a file, that is like 1,2,4,4,4,2,1,1,1 ...
> or are there always the same number of frames packed together?
> if it can change then they must be split in the demuxer or parser as
> the alternative will make muxing in some containers much harder
> if none of the above applied then its not strictly needed to spit but
> its IMHO still a good idea to split them ...
I think it's the same case as swf_adpcm, there can't be to many audio
tags per time unit for the flv format when it's muxed with video. The
nellymoser format also has 3 different sample rates, 8,11,22 which could
map to 1,2 and 4 times 64 sizes. If that is the case then a mux to
another format and back would work without any trouble. If the blocks
where split then a muxer would need to concatenate the blocks depending
on the sample rate. So I actually think the right way to do it is not to
split the tags into single frames.
All in all this is just guesses as there is no spec.
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