[FFmpeg-devel] [PATCH] Set CODEC_CAP_SUBFRAMES for adpcm decoders

Måns Rullgård mans
Thu Jan 21 17:42:27 CET 2010

Michael Niedermayer <michaelni at gmx.at> writes:

> On Thu, Jan 21, 2010 at 02:12:26PM +0000, M?ns Rullg?rd wrote:
>> Benjamin Larsson <banan at ludd.ltu.se> writes:
>> > M?ns Rullg?rd wrote:
>> >> I thought adpcm was one of those non-byte-aligned codecs, at least
>> >> some variants.
>> >
>> > It is.
>> Which means frame-splitting is not generally possible.
> ADPCM in general comes in frames with a header of an initial sample
> and a series of adaptive delta coded fixed length (generally
> 4 bit) symbols
> but there are exceptions. The general case though certainly can be split

General in this context means something that is always true.  If there
exist adpcm streams with non-byte-aligned frames, they cannot be split
in the general case, which includes these streams.

It may be that in the _majority_ of streams can be split, but unless
there's an easy way to determine this without actually trying it, I
don't think we should be requiring it.

M?ns Rullg?rd
mans at mansr.com

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