On Tue, 2 Jan 2018 22:27:49 +0800
Jiejun Zhang <zhangjiejun1...@gmail.com> wrote:
> On Tue, Jan 2, 2018 at 8:03 PM, Carl Eugen Hoyos <ceffm...@gmail.com> wrote:
> > 2018-01-02 8:52 GMT+01:00 <zhangjiejun1...@gmail.com>:
> >
> >> @@ -565,6 +579,10 @@ static av_cold int ffat_close_encoder(AVCodecContext
> >> *avctx)
> >> ff_bufqueue_discard_all(&at->frame_queue);
> >> ff_bufqueue_discard_all(&at->used_frame_queue);
> >> ff_af_queue_close(&at->afq);
> >> + if (at->audio_data_buf_size > 0) {
> >> + at->audio_data_buf_size = 0;
> >> + av_free(at->audio_data_buf);
> >> + }
> >
> > The if() looks unnecessary.
>
> Yes. I'll remove it. Thanks for pointing it out.
>
> > Could you explain what this patch changes?
> > From a quick look, until now a buffer a was used with a calculated size x.
> > After the patch, a buffer b with the same calculated size x is allocated,
> > and x bytes are copied from a to b.
> > What do I miss?
>
> Although undocumented, AudioToolbox seems to require the data supplied
> by the callback (i.e. ffat_encode_callback) being unchanged until the
> next time the callback is called. In the old implementation, the
> AVBuffer backing the frame is recycled after the frame is freed, and
> somebody else (maybe the decoder) will write into the AVBuffer and
> change the data. AudioToolbox then encodes some wrong data and noise
> is produced. Copying the data to a separate buffer solves this
> problem.
This should be in the commit message.
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