[Live-devel] openRTSP producing bad video files

[Ron McOuat]

Ross Finlayson wrote:
> We don't make available old versions of the code, and offer absolutely 
> no support for old versions.  Everyone should work with the newest 
> version of the code.

I am still working on this to find the cause of what I am observing and 
have not finished fully identifying this. Here is what I have found so 
far in case that is enough.

Axis camera is set for 320x240 image size at 7 frames/sec. The GOV 
setting is 8 which I believe means an I frame followed by 7 P frames and 
then the cycle repeats.

I tested several versions of live555 and was only able to reproduce this 
in the version that is current 2008-07-25.

If I play the movie produced back in QuickTime player and step it one 
frame at a time the seconds display embedded in the image advances one 
second for each frame which is not right. After a few seconds of 
playback wall clock time or 10-12 seconds of video frame time the 
playback becomes normal with respect to watching time advance on the 
playback. I also see the full 7 frames for each second in the image 
while single stepping in the later part of the video instead of just one 
frame like in the beginning. VLC also plays the recorded files the same way.

When recording from an Axis camera it is like joining a live broadcast 
in process, the first frames could be P frames because on playback I 
have observed green screen until the first I frame comes in. I mention 
this in case it is relevant.

The annoying part of finding this is it doesn't always happen, on 
average about 50% of the recordings have this high speed playback on the 
front. It could be the initial part is very short in some cases and 
difficult to observe. I tested 10 times with each version to get some 
level of confidence the fast video was not on the front for recordings 
made by earlier versions.

The camera and recording system (Mac Book Pro 2.33 GHz) are on the same 
100 MBit/sec LAN.

Looking at a diff of the source to the previous version the only thing I 
can see that remotely looks like it might affect what is recorded is the 
class MultiFramedRTPSource was changed to treat the first packet as 
having packet loss.

My next step is to patch that change out and see if the recorded video 
files still act the same or clear up.

Is there a utility out there that will scan over a recorded stream in a 
file and show the frames by type etc. I could record in a format other 
than QuickTime and use a different playback program? I got Dumpster from 
the Apple site but it doesn't get into the frame details. I suppose I 
could write one but other work has higher priority.

Any comments or suggestions welcome.

Ron