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avformat/rtpdec: explicit timestamp wraparound handling

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Change delta_timestamp to int32_t and add explicit cast to handle
RTP timestamp wraparound correctly. This fixes implementation-defined
behavior when computing negative timestamp differences due to 32-bit
wraparound.

Signed-off-by: Clément Péron <peron.clem@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Clément Péron
2025-06-08 17:07:37 +02:00
committed by Michael Niedermayer
parent 3f1f9db7f5
commit 52441bd4cd
1 changed files with 4 additions and 2 deletions
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6
libavformat/rtpdec.c
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@ -597,6 +597,7 @@ static int rtp_set_prft(RTPDemuxContext *s, AVPacket *pkt, uint32_t timestamp) {
return AVERROR(ENOMEM); return AVERROR(ENOMEM);
rtcp_time = ff_parse_ntp_time(s->last_rtcp_ntp_time) - NTP_OFFSET_US; rtcp_time = ff_parse_ntp_time(s->last_rtcp_ntp_time) - NTP_OFFSET_US;
/* Cast to int32_t to handle timestamp wraparound correctly */
delta_timestamp = (int32_t)(timestamp - s->last_rtcp_timestamp); delta_timestamp = (int32_t)(timestamp - s->last_rtcp_timestamp);
delta_time = av_rescale_q(delta_timestamp, s->st->time_base, AV_TIME_BASE_Q); delta_time = av_rescale_q(delta_timestamp, s->st->time_base, AV_TIME_BASE_Q);
@ -624,10 +625,11 @@ static void finalize_packet(RTPDemuxContext *s, AVPacket *pkt, uint32_t timestam
if (s->last_rtcp_ntp_time != AV_NOPTS_VALUE && s->ic->nb_streams > 1) { if (s->last_rtcp_ntp_time != AV_NOPTS_VALUE && s->ic->nb_streams > 1) {
int64_t addend; int64_t addend;
int delta_timestamp; int32_t delta_timestamp;
/* compute pts from timestamp with received ntp_time */ /* compute pts from timestamp with received ntp_time */
delta_timestamp = timestamp - s->last_rtcp_timestamp; /* Cast to int32_t to handle timestamp wraparound correctly */
delta_timestamp = (int32_t)(timestamp - s->last_rtcp_timestamp);
/* convert to the PTS timebase */ /* convert to the PTS timebase */
addend = av_rescale(s->last_rtcp_ntp_time - s->first_rtcp_ntp_time, addend = av_rescale(s->last_rtcp_ntp_time - s->first_rtcp_ntp_time,
s->st->time_base.den, s->st->time_base.den,