[FFmpeg-devel] [PATCH 01/10] avformat/mux: Only prepare input packet if there is a packet

[Andreas Rheinhardt]

Marton Balint:
> 
> 
> On Tue, 31 Mar 2020, Andreas Rheinhardt wrote:
> 
>> It is unnecessary to call prepare_input_packet if there is no packet as
>> it doesn't do anything, except when the currently inactive code guarded
>> by !FF_API_COMPUTE_PKT_FIELDS2 || !FF_API_LAVF_AVCTX becomes active:
>> Then attempting to access pkt->stream_index will crash.
>>
>> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
>> ---
>> This works very well together with Marton's patch #4 [1]:
>> write_packets_common(): The prepare_input_packet() call can be moved
>> into write_packets_common(). Unfortunately, it's not compatible with #5
>> [2] as-is, but I think I have a solution for this.
>>
>> [1]: https://ffmpeg.org/pipermail/ffmpeg-devel/2020-March/259203.html
>> [2]: https://ffmpeg.org/pipermail/ffmpeg-devel/2020-March/259204.html
>>
>> libavformat/mux.c | 22 ++++++++++------------
>> 1 file changed, 10 insertions(+), 12 deletions(-)
>>
>> diff --git a/libavformat/mux.c b/libavformat/mux.c
>> index bfd1bf491b..814d773b9d 100644
>> --- a/libavformat/mux.c
>> +++ b/libavformat/mux.c
>> @@ -771,9 +771,6 @@ static int write_packet(AVFormatContext *s,
>> AVPacket *pkt)
>>
>> static int check_packet(AVFormatContext *s, AVPacket *pkt)
>> {
>> -    if (!pkt)
>> -        return 0;
>> -
>>     if (pkt->stream_index < 0 || pkt->stream_index >= s->nb_streams) {
>>         av_log(s, AV_LOG_ERROR, "Invalid packet stream index: %d\n",
>>                pkt->stream_index);
>> @@ -887,10 +884,6 @@ int av_write_frame(AVFormatContext *s, AVPacket
>> *pkt)
>> {
>>     int ret;
>>
>> -    ret = prepare_input_packet(s, pkt);
>> -    if (ret < 0)
>> -        return ret;
>> -
>>     if (!pkt) {
>>         if (s->oformat->flags & AVFMT_ALLOW_FLUSH) {
>>             ret = s->oformat->write_packet(s, NULL);
>> @@ -902,6 +895,10 @@ int av_write_frame(AVFormatContext *s, AVPacket
>> *pkt)
>>         return 1;
>>     }
>>
>> +    ret = prepare_input_packet(s, pkt);
>> +    if (ret < 0)
>> +        return ret;
>> +
>>     ret = do_packet_auto_bsf(s, pkt);
>>     if (ret <= 0)
>>         return ret;
>> @@ -1191,12 +1188,12 @@ int av_interleaved_write_frame(AVFormatContext
>> *s, AVPacket *pkt)
>> {
>>     int ret, flush = 0;
>>
>> -    ret = prepare_input_packet(s, pkt);
>> -    if (ret < 0)
>> -        goto fail;
>> -
>>     if (pkt) {
>> -        AVStream *st = s->streams[pkt->stream_index];
>> +        AVStream *st;
> 
> Delaying the initialization is not needed as far as I see, so you can
> keep this as is.
> 
Applied with that change. Thanks.

- Andreas