[FFmpeg-devel] [PATCH 1/2] doc/examples/transcode_aac: Don't ignore last encoded frame

[Andreas Unterweger]

> On 02.03.2022 13:27 Paul B Mahol <onemda at gmail.com> wrote:
>
>
> On Wed, Mar 2, 2022 at 1:18 PM Andreas Unterweger <dustsigns at gmail.com>
> wrote:
>
> > > On 02.03.2022 12:55 Paul B Mahol <onemda at gmail.com> wrote:
> > > > >               do {
> > > > > -                data_written = 0;
> > > >
> > >
> > > why this is removed ?
> > >
> > >
> > > > >                   if (encode_audio_frame(NULL, output_format_context,
> > > > >                                          output_codec_context,
> > > > &data_written))
> > > > >                       goto cleanup;
> >
> > It is removed because the function encode_audio_frame (next line)
> > already sets data_written as an output value (this is also in the
> > documentation of this function). It is thus not needed to initialize
> > data_written a second time outside of the function.
> >
>
> Note that it does not set it immediately at start, but later, and upon
> error it is left untouched/uninitialized.
>

In case of an error, an error code is returned from the function and
the output value has no meaning. In the calling function, the cleanup
is invoked and data_written is not used (as it would make no sense to
use it in case of an error, anyway).

This behavior is the same as with the decode_audio_frame function. The
only difference is that the finished = 0 initialization in line 830 is
needed to avoid to forcefully flush the decoder in lines 865ff on an
empty input file.