[FFmpeg-devel] [PATCH 1/4] avcodec/mediacodecdec: clarify delay_flush specific code

[Aman Gupta]

On Tue, Apr 24, 2018 at 2:11 PM, Jan Ekström <jeebjp at gmail.com> wrote:

> On Tue, Apr 24, 2018 at 11:59 PM, Aman Gupta <ffmpeg at tmm1.net> wrote:
> > From: Aman Gupta <aman at tmm1.net>
> >
> > ---
> >  libavcodec/mediacodecdec.c        | 24 +++---------------------
> >  libavcodec/mediacodecdec_common.c | 12 ++++++++++++
> >  2 files changed, 15 insertions(+), 21 deletions(-)
> >
> > diff --git a/libavcodec/mediacodecdec.c b/libavcodec/mediacodecdec.c
> > index 0d4a853f07..e5d3e6a0af 100644
> > --- a/libavcodec/mediacodecdec.c
> > +++ b/libavcodec/mediacodecdec.c
> > @@ -419,27 +419,9 @@ static int mediacodec_receive_frame(AVCodecContext
> *avctx, AVFrame *frame)
> >      MediaCodecH264DecContext *s = avctx->priv_data;
> >      int ret;
> >
> > -    /*
> > -     * MediaCodec.flush() discards both input and output buffers, thus
> we
> > -     * need to delay the call to this function until the user has
> released or
> > -     * renderered the frames he retains.
> > -     *
> > -     * After we have buffered an input packet, check if the codec is in
> the
> > -     * flushing state. If it is, we need to call
> ff_mediacodec_dec_flush.
> > -     *
> > -     * ff_mediacodec_dec_flush returns 0 if the flush cannot be
> performed on
> > -     * the codec (because the user retains frames). The codec stays in
> the
> > -     * flushing state.
> > -     *
> > -     * ff_mediacodec_dec_flush returns 1 if the flush can actually be
> > -     * performed on the codec. The codec leaves the flushing state and
> can
> > -     * process again packets.
> > -     *
> > -     * ff_mediacodec_dec_flush returns a negative value if an error has
> > -     * occurred.
> > -     *
> > -     */
> > -    if (ff_mediacodec_dec_is_flushing(avctx, s->ctx)) {
> > +    /* in delay_flush mode, wait until the user has released or rendered
> > +       all retained frames. */
> > +    if (s->delay_flush && ff_mediacodec_dec_is_flushing(avctx,
> s->ctx)) {
> >          if (!ff_mediacodec_dec_flush(avctx, s->ctx)) {
> >              return AVERROR(EAGAIN);
> >          }
>
> The commit message makes it sound as if you are only improving the
> documentation, while you have now added an additional limitation here
> (only check for flushing if delay_flush is true), so you might want to
> detail on the "What & Why" in the commit message. Otherwise looks
> alright.
>

There are no functional changes in this patch.

Previously, ff_mediacodec_dec_is_flushing() would only ever be true
if the user had set delay_flush. By adding that to the if statement, it
makes it clearer that this
part of the code is only in effect when that special option is set.

Aman


>
> Jan
>