[FFmpeg-devel] [PATCH] DCA floating point output

Alex Converse alex.converse
Mon Apr 26 04:21:34 CEST 2010

2010/4/25 M?ns Rullg?rd <mans at mansr.com>:
> "FB2000" <flybird2k at gmail.com> writes:
>> I understand a patch like this one had been discussed at January
>> 2008 but it used a compiling switch
>> which by itself might bring some confusion.
>> Since DCA source PCM resolution is either 16, 20 or 24 bits, and the
>> DCA decoder uses float internally, it's clear that float is a much
>> better output format than currently used int16_t. My point is that
>> we should change to float directly without using any switch. By
>> changing
>> avctx->sample_fmt = SAMPLE_FMT_S16;
>> to
>> avctx->sample_fmt = SAMPLE_FMT_FLT;
>> at dca_decode_init(), callers like ffmpeg or ffplay understand the
>> output format correctly thus nothing need to be modified out of
>> dca.c.
>> I've also removed codes related to float_to_int16_interleave since
>> it's no longer needed for the output.
>> I hope this patch could find its way into libavcodec, so that we
>> could finally get a better quality DCA decoder.
> Until sensible audio format conversion code is in place, this is
> utterly unacceptable. ?It would make the decoder at least 5x slower on
> some systems.

Only in the *particular case* where int16 output is required.

The rest of the universe shouldn't be held under the tyranny of people
with shitty hardware who want int16 output.

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