[vlc-devel] [PATCH] avcodec: avoid division by zero

[Ilkka Ollakka]

Hi,

On Fri, May 03, 2013 at 02:31:49AM -0400, Tristan Matthews wrote:
> Setting align to 0 to get default behaviour only works as of libavutil 51.27.2
> See libav commit 0109a09dc3850eb5dbff84a7bb50eb252a5a8f22
> Fixes #8508.


This patch assumes that same functionality is in ffmpeg from 51.0.0
onwards, which seems to be wrong. LIBAVUTIL_VERSION_CHECK is used to
check both ffmpeg and libav at the same time in vlc code. You can see
the LIBAVUTIL_VERSION_CHECK macro in avcommon.h file.

> ---
>  modules/codec/avcodec/encoder.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)

> diff --git a/modules/codec/avcodec/encoder.c b/modules/codec/avcodec/encoder.c
> index 5c06385..80bce30 100644
> --- a/modules/codec/avcodec/encoder.c
> +++ b/modules/codec/avcodec/encoder.c
> @@ -1120,6 +1120,11 @@ static block_t *EncodeAudio( encoder_t *p_enc, block_t *p_aout_buf )
>      {
>          //How much we need to copy from new packet
>          const int leftover = leftover_samples * p_enc->fmt_in.audio.i_channels * p_sys->i_sample_bytes;
> +#if LIBAVUTIL_VERSION_CHECK( 51,27,2,0,0 )
> +        const int align = 0;
> +#else
> +        const int align = 1;
> +#endif

>          AVPacket packet = {0};
>          avcodec_get_frame_defaults( p_sys->frame );
> @@ -1146,7 +1151,7 @@ static block_t *EncodeAudio( encoder_t *p_enc, block_t *p_aout_buf )
>          if( avcodec_fill_audio_frame( p_sys->frame, p_enc->fmt_in.audio.i_channels,
>                  p_sys->p_context->sample_fmt, p_sys->p_buffer,
>                  leftover + buffer_delay,
> -                0) < 0 )
> +                align) < 0 )
>              msg_Err( p_enc, "filling error on fillup" );

>          buffer_delay = 0;
> @@ -1210,6 +1215,11 @@ static block_t *EncodeAudio( encoder_t *p_enc, block_t *p_aout_buf )
>             ( p_sys->b_variable && p_aout_buf->i_nb_samples ) )
>      {
>          AVPacket packet = {0};
> +#if LIBAVUTIL_VERSION_CHECK( 51,27,2,0,0 )
> +        const int align = 0;
> +#else
> +        const int align = 1;
> +#endif

>          if( unlikely( p_aout_buf->i_pts > VLC_TS_INVALID &&
>                        p_aout_buf->i_pts != date_Get( &p_sys->buffer_date ) ) )
> @@ -1234,7 +1244,7 @@ static block_t *EncodeAudio( encoder_t *p_enc, block_t *p_aout_buf )
>                                      p_sys->p_context->sample_fmt,
>                                      p_sys->b_planar ? p_sys->p_buffer : p_aout_buf->p_buffer,
>                                      __MIN(p_sys->i_buffer_out, p_aout_buf->i_buffer),
> -                                    0) < 0 )
> +                                    align) < 0 )
>                   msg_Err( p_enc, "filling error on encode" );

>          p_aout_buf->p_buffer     += (p_sys->frame->nb_samples * p_enc->fmt_in.audio.i_channels * p_sys->i_sample_bytes);
-- 
Ilkka Ollakka
Think of prototypes as a funny markup language--the interpretation is
left up to the rendering engine.
		-- Larry Wall in <199710221710.KAA24242 at wall.org>
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