Question: Does ATSC TS have multiple video streams?

[erik]

I am making some good progress in learning Comskip how to read TS input.
DVB-T is working ok now (for the streams I tested with) and ATSC works both for MPEG audio and AC3 audio.
One of the test streams does contain multiple video streams. The same content but one in 60fps HD and one in 30fps SD.
This is diffucult because I now have to find a way to decide which stream to use. Or I will take the first one I encounter.
Do many DVB-T or ATSC TS carry multiple video streams?
Or is it possible to set your recording such that only one video and audio stream is present in the recording?

[sub]

Nearly all DVB and ATSC transport streams will contain multiple video streams. I have been curious how you knew which stream to process.

[erik]

As long as the content of the streams is the same and they differ only in resolutions its not a real problem, I actually can take the stream with the lowest resolution.

For streams that contain multiple streams with different content someone (you?) will have to select the PID's related to the wanted program. Otherwise one will waste space during the recording.

What is your approach?

[sub]

As long as the content of the streams is the same and they differ only in resolutions its not a real problem, I actually can take the stream with the lowest resolution.

Thats not common. Usually they contain different channels.

For streams that contain multiple streams with different content someone (you?) will have to select the PID's related to the wanted program. Otherwise one will waste space during the recording.

What is your approach?

In GB-PVR with DVB, when the user first sets up their capture sources, GB-PVR scans each transport stream locating all of the channels they contain and gives the user a list of the channels found and they can select which ones they want to use. Each of these channel definition contains several pieces of information such as service ID, PMT PID, Video PID, Audio PIDs. When the user views TV or makes recording, GB-PVR programmes the demux to use the appropriate PIDs based on the channel.

[erik]

Each of these channel definition contains several pieces of information such as service ID, PMT PID, Video PID, Audio PIDs. When the user views TV or makes recording, GB-PVR programmes the demux to use the appropriate PIDs based on the channel.

Indeed, so I did read the MPEG DVB standard and the ATSC standard and wrote a demux reading the PMT, Video PID and Audio PID.

However, if you implement recording of DVB or ATSC, will you record the TS containing multiple channels or will you run a filter that disects the TS into only the info for the one channel of interrest to save disk space?

Otherwise comskip must be told which channel to read from the TS.
I did not yet implement this.

What are your ideas?

[sub]

GB-PVR doesnt record Transport Stream files. It records .MPG Program Stream files (or .DVR-MS files), which only contain the appropriate streams. During recording I demux only the streams needed for the required channel, and then remux to a program stream which is saved to disk.

[erik]

OK,
so for GBPVR there will never be the need for Comskip to decode TS.
Thanks.

[sub]

No, not in the near future.

[sub]

Does comskip handle DVR-MS files? If not, I would think this would be worth while investing the time on. Given some changes Microsoft has got coming up, recording to DVR-MS is probably going to become a lot more common in the future...

[erik]

Where can I find the information?