Andreas Rheinhardt:
> 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.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
>>>
>> Another ping for the three unmerged patches of this patchset.
>>
>> - Andreas
>>
> Another ping for the two unmerged patches of this patchset; and also
> for the other patch fixing uninitialized reads in the vobsub demuxer:
> https://ffmpeg.org/pipermail/ffmpeg-devel/2019-October/251961.html
>
> - Andreas
>
Ping.
- Andreas
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