[FFmpeg-devel] [PATCH 2/4] avformat/mpeg: Remove secondary packet for reading VobSub

[Andreas Rheinhardt]

Andreas Rheinhardt:
> Andreas Rheinhardt:
>> When vobsub_read_packet() reads a packet, it uses a dedicated AVPacket
>> to get the subtitle timing and position from an FFDemuxSubtitlesQueue
>> (which has been filled with this data during reading the idx file in
>> vobsub_read_header); afterwards the actual subtitle data is read into
>> the packet destined for output and the timing and position are copied
>> to this packet. Afterwards, the local packet is unreferenced.
>>
>> This can be simplified: Simply use the output packet to get the timing
>> and position from the FFDemuxSubtitlesQueue. The packet's size will be
>> zero afterwards, so that it can be directly used to read the actual
>> subtitle data. This makes copying the packet fields as well as
>> unreferencing the local packet unecessary and also removes an instance
>> of usage of sizeof(AVPacket) in libavformat.
>>
>> The only difference is that the returned packet will already be flagged
>> as a keyframe. This currently only happens in compute_pkt_fields().
>>
>> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
>> ---
>>  libavformat/mpeg.c | 23 +++++++----------------
>>  1 file changed, 7 insertions(+), 16 deletions(-)
>>
>> diff --git a/libavformat/mpeg.c b/libavformat/mpeg.c
>> index bd182e4429..7daa72f7ce 100644
>> --- a/libavformat/mpeg.c
>> +++ b/libavformat/mpeg.c
>> @@ -912,7 +912,6 @@ static int vobsub_read_packet(AVFormatContext *s, AVPacket *pkt)
>>      FFDemuxSubtitlesQueue *q;
>>      AVIOContext *pb = vobsub->sub_ctx->pb;
>>      int ret, psize, total_read = 0, i;
>> -    AVPacket idx_pkt = { 0 };
>>  
>>      int64_t min_ts = INT64_MAX;
>>      int sid = 0;
>> @@ -927,24 +926,22 @@ static int vobsub_read_packet(AVFormatContext *s, AVPacket *pkt)
>>          }
>>      }
>>      q = &vobsub->q[sid];
>> -    ret = ff_subtitles_queue_read_packet(q, &idx_pkt);
>> +    /* The returned packet will have size zero,
>> +     * so that it can be directly used with av_grow_packet. */
>> +    ret = ff_subtitles_queue_read_packet(q, pkt);
>>      if (ret < 0)
>>          return ret;
>>  
>>      /* compute maximum packet size using the next packet position. This is
>>       * useful when the len in the header is non-sense */
>>      if (q->current_sub_idx < q->nb_subs) {
>> -        psize = q->subs[q->current_sub_idx].pos - idx_pkt.pos;
>> +        psize = q->subs[q->current_sub_idx].pos - pkt->pos;
>>      } else {
>>          int64_t fsize = avio_size(pb);
>> -        psize = fsize < 0 ? 0xffff : fsize - idx_pkt.pos;
>> +        psize = fsize < 0 ? 0xffff : fsize - pkt->pos;
>>      }
>>  
>> -    avio_seek(pb, idx_pkt.pos, SEEK_SET);
>> -
>> -    av_init_packet(pkt);
>> -    pkt->size = 0;
>> -    pkt->data = NULL;
>> +    avio_seek(pb, pkt->pos, SEEK_SET);
>>  
>>      do {
>>          int n, to_read, startcode;
>> @@ -968,7 +965,7 @@ static int vobsub_read_packet(AVFormatContext *s, AVPacket *pkt)
>>          total_read += pkt_size;
>>  
>>          /* the current chunk doesn't match the stream index (unlikely) */
>> -        if ((startcode & 0x1f) != s->streams[idx_pkt.stream_index]->id)
>> +        if ((startcode & 0x1f) != s->streams[pkt->stream_index]->id)
>>              break;
>>  
>>          ret = av_grow_packet(pkt, to_read);
>> @@ -980,16 +977,10 @@ static int vobsub_read_packet(AVFormatContext *s, AVPacket *pkt)
>>              pkt->size -= to_read - n;
>>      } while (total_read < psize);
>>  
>> -    pkt->pts = pkt->dts = idx_pkt.pts;
>> -    pkt->pos = idx_pkt.pos;
>> -    pkt->stream_index = idx_pkt.stream_index;
>> -
>> -    av_packet_unref(&idx_pkt);
>>      return 0;
>>  
>>  fail:
>>      av_packet_unref(pkt);
>> -    av_packet_unref(&idx_pkt);
>>      return ret;
>>  }
>>  
>>
> Ping.
> 
> - Andreas
> 
Another ping for the three unmerged patches of this patchset.

- Andreas