[FFmpeg-devel] [PATCH] avcodec/(null|opus)_bsf: Use ff_bsf_get_packet_ref() directly

[Andreas Rheinhardt]

James Almer:
> On 5/8/2020 7:52 AM, Andreas Rheinhardt wrote:
>> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
>> ---
>> The change to the documentation would be unnecessary if James' patch
>> https://ffmpeg.org/pipermail/ffmpeg-devel/2020-April/260984.html were
>> applied. But it is only internal documentation, so changing and
>> reverting it is easy.
> 
> How does my patch change the success return values of
> ff_bsf_get_packet_ref()?
> 
It doesn't; yet av_bsf_receive_packet() documents that it returns 0 on
success. Values > 0 are against its documentation. Had
ff_bsf_get_packet_ref() ever returned values > 0, then forwarding its
return value without filtering it (as is done currently) would not be
allowed. Therefore this patch aligns the documentation of
ff_bsf_get_packet_ref() with the one from av_bsf_receive_packet().
Your patch meanwhile would filter any return values > 0 of an
AVBitStreamFilter.filter function away.

>>
>>  libavcodec/bsf.h               | 2 +-
>>  libavcodec/null_bsf.c          | 7 +------
>>  libavcodec/opus_metadata_bsf.c | 7 +------
>>  3 files changed, 3 insertions(+), 13 deletions(-)
>>
>> diff --git a/libavcodec/bsf.h b/libavcodec/bsf.h
>> index af035eee44..d04f1d3068 100644
>> --- a/libavcodec/bsf.h
>> +++ b/libavcodec/bsf.h
>> @@ -35,7 +35,7 @@ int ff_bsf_get_packet(AVBSFContext *ctx, AVPacket **pkt);
>>   * @param ctx pointer to AVBSFContext of filter
>>   * @param pkt pointer to packet to move reference to
>>   *
>> - * @return 0>= on success, negative AVERROR in case of failure
>> + * @return 0 on success, negative AVERROR in case of failure
> 
> This change is ok, but I don't think it's relevant to this patch.
> 
>>   */
>>  int ff_bsf_get_packet_ref(AVBSFContext *ctx, AVPacket *pkt);
>>  
>> diff --git a/libavcodec/null_bsf.c b/libavcodec/null_bsf.c
>> index 24d26dfb1a..37f4640c87 100644
>> --- a/libavcodec/null_bsf.c
>> +++ b/libavcodec/null_bsf.c
>> @@ -24,12 +24,7 @@
>>  #include "avcodec.h"
>>  #include "bsf.h"
>>  
>> -static int null_filter(AVBSFContext *ctx, AVPacket *pkt)
>> -{
>> -    return ff_bsf_get_packet_ref(ctx, pkt);
>> -}
>> -
>>  const AVBitStreamFilter ff_null_bsf = {
>>      .name           = "null",
>> -    .filter         = null_filter,
>> +    .filter         = ff_bsf_get_packet_ref,
>>  };
>> diff --git a/libavcodec/opus_metadata_bsf.c b/libavcodec/opus_metadata_bsf.c
>> index 867ad830d3..d22db54f30 100644
>> --- a/libavcodec/opus_metadata_bsf.c
>> +++ b/libavcodec/opus_metadata_bsf.c
>> @@ -25,11 +25,6 @@ typedef struct OpusBSFContext {
>>      int gain;
>>  } OpusBSFContext;
>>  
>> -static int opus_metadata_filter(AVBSFContext *bsfc, AVPacket *pkt)
>> -{
>> -    return ff_bsf_get_packet_ref(bsfc, pkt);
>> -}
>> -
>>  static int opus_metadata_init(AVBSFContext *bsfc)
>>  {
>>      OpusBSFContext *s = bsfc->priv_data;
>> @@ -67,6 +62,6 @@ const AVBitStreamFilter ff_opus_metadata_bsf = {
>>      .priv_data_size = sizeof(OpusBSFContext),
>>      .priv_class     = &opus_metadata_class,
>>      .init           = &opus_metadata_init,
>> -    .filter         = &opus_metadata_filter,
>> +    .filter         = &ff_bsf_get_packet_ref,
>>      .codec_ids      = codec_ids,
>>  };
> 
> LGTM otherwise.
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