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Transport stream video packets have no duration

Transport stream video packets have no duration

Postby cavalino » Sun Nov 26, 2017 1:41 am

I've been using my TBS2603 with MythTV, and it's been great except for one problem.

As far as I understand, MythTV seems to rely on the duration information of each video packet (or frame?) in order to make it possible to seek back and forth accurately within a recording. Sometimes with the transport stream that comes as part of an over-the-air broadcast, the framerate will change in the middle, say from 60fps to 30fps, and then back to 60fps, especially with commercials. So the framerate of the video overall can't really be used to co-relate position in the recording file with time because of this. Hence, I think they use this packet or frame duration information within the video stream to do this accurately.

From what I can tell, the video within a transport stream produced by the TBS2603 doesn't contain any packet duration at all.

I am using the ffprobe utility (part of the ffmpeg tool suite on Linux) to examine the content of the video packets from the TBS2603, like this:

ffprobe -i tbs2603_file.ts -show_packets -select_streams v

You then get a bunch of output like this:

...
[PACKET]
codec_type=video
stream_index=0
pts=8098077717
pts_time=89978.641300
dts=8098077717
dts_time=89978.641300
duration=N/A
duration_time=N/A
convergence_duration=N/A
convergence_duration_time=N/A
size=2354
pos=14633920
flags=_
[/PACKET]
...

See how the attributes for duation are listed as N/A? On transport streams from other types of sources, these duration attributes are filled in.

Is there any chance this can be corrected with a new firmware release?

Thanks.
cavalino
 
Posts: 3
Joined: Tue Nov 21, 2017 11:09 am

Re: Transport stream video packets have no duration

Postby echomay » Mon Nov 27, 2017 10:56 am

Hi,Thanks for the information, we willcheck about it later, if we have some news about it, we will contact you.
echomay
 
Posts: 75
Joined: Tue Apr 26, 2016 9:24 am

Re: Transport stream video packets have no duration

Postby cavalino » Mon Dec 17, 2018 10:14 pm

When I originally posted this, the TBS2603 firmware version was 1.1.12.

Now it has been updated to 1.1.87.

Is this problem fixed in the 1.1.87 firmware version?
cavalino
 
Posts: 3
Joined: Tue Nov 21, 2017 11:09 am

Re: Transport stream video packets have no duration

Postby echomay » Thu Dec 20, 2018 4:09 pm

Hi,
For our system, when the input framerate changed, the device need reset parameters and restart, so, the stream will auto restart. so we not suggest the encoder be using frome the source which framrate always changed.
echomay
 
Posts: 75
Joined: Tue Apr 26, 2016 9:24 am

Re: Transport stream video packets have no duration

Postby cavalino » Thu May 02, 2019 10:31 am

No, the problem is not having to support when the input framerate changes.

Even when the input framerate stays constant for the duration of the input stream, the output stream should have the packet duration filled in properly, and not left blank like it is currently.

Can you do this?
cavalino
 
Posts: 3
Joined: Tue Nov 21, 2017 11:09 am

Re: Transport stream video packets have no duration

Postby echomay » Mon May 13, 2019 10:18 am

Hi,
We will try to find a way to add the duration in to the stream.
echomay
 
Posts: 75
Joined: Tue Apr 26, 2016 9:24 am


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