Opened 13 years ago

Closed 13 years ago

Last modified 13 years ago

#16 closed defect (fixed)

"non-monotonically increasing dts" because of corrupt rtptime

Reported by: Ilya I Owned by: Michael Niedermayer
Priority: important Component: ffmpeg
Version: git Keywords:
Cc: Blocked By:
Blocking: Reproduced by developer: no
Analyzed by developer: yes


I'm using ffmpeg-r26400-swscale-r32676.
I've found a bug in libavformat/rtsp.c, function rtsp_parse_rtp_info(): rtptime and seq values from RTSP interpreted as signed long, strtol() function is used to read these values. Problem is that these values are unsigned, and when >0x7fffffff, strtol() returns wrong value. This causes various errors (mainly "non monotonically incresing dts" complaint).
unsigned version strtoul() should be used to read these values. Patch attached

Attachments (1)

rtsp.c.patch (1.5 KB ) - added by Ilya I 13 years ago.

Download all attachments as: .zip

Change History (5)

by Ilya I, 13 years ago

Attachment: rtsp.c.patch added


comment:1 by Michael Niedermayer, 13 years ago

Analyzed by developer: set

Patch looks good to me
i wonder if 32bit is actually enough, is the rfc saying somewhere how many bits one needs?

comment:2 by Carl Eugen Hoyos, 13 years ago

Resolution: fixed
Status: newclosed

Patch applied, thank you!

I did not find any reference to 32 or 64bit or the needed range for seq and rtptime in rfc 2326.

comment:3 by Ilya I, 13 years ago

According to rfc 1889 (p.11), RTP timestamps are 32 bit long. It's not clear from RFC text, whether it should be signed or unsigned, but according to implementation example in Annex A, it is defined as 32-bit unsigned int.

u_int32 ts; /* timestamp */

Rtptime field in rtsp represent initial value of RTP timestamp, so it should be 32 bit unsigned value too.
Sequence number is defined as 16 bit number, or

u_int16 seq; /* sequence number */

Last edited 13 years ago by Ilya I (previous) (diff)

comment:4 by wlzh, 13 years ago

this ticket is resolved by the newest version of libav.

i test just now.

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