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.rheinha...@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
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