Connect MPEG-2 demux filter in Directshow graph?

[bgowland]

As GB-PVR doesn't support recording DVB-T radio (yet), I thought I'd have a play at it myself. I can build a working graph in Graphedit and tune one of my Nova-T cards to the radio channel and capture to an mp3 file writer. So far so good.

I then tried using DirectShowLib (C# 'wrapper' for directshow available from Sourceforge). So far I can add the MS DVB-T Network Provider filter, Nova-t Tuner/Demod, Nova-T Capture and MPEG-2 demux to the graph and connect the first three successfully together. No matter what I do, however, I can't connect the MPEG2 Transport output pin of the capture filter to the MPEG2 Stream input pin of the mpeg2 demux. I don't get any errors, just nothing happens. If I 'break' in debug and connect to the remote graph I can, however, render the capture filter mpeg2 TS output pin using Graphedit and it happily hooks up with the mpeg2 demux.

I know this is all a bit vague but what I'm asking is...is there anything special about the default MPEG2 Demux that means I have to treat it differently? I'm specifying the pin media type/subtype/format by name or GUID as shown in filter properties in Graphedit.

There's something I want to record on Boxing Day but it's no big deal, I could always record from my STB to VCR or even just run the graph manually in graphedit.

You'd think I'd find something better to do on Christmas Eve than programming wouldn't you? Sad, sad man.

Cheers,
Brian

[funkybro_uk]

As GB-PVR doesn't support recording DVB-T radio (yet), I thought I'd have a play at it myself. I can build a working graph in Graphedit and tune one of my Nova-T cards to the radio channel and capture to an mp3 file writer. So far so good.

I then tried using DirectShowLib (C# 'wrapper' for directshow available from Sourceforge). So far I can add the MS DVB-T Network Provider filter, Nova-t Tuner/Demod, Nova-T Capture and MPEG-2 demux to the graph and connect the first three successfully together. No matter what I do, however, I can't connect the MPEG2 Transport output pin of the capture filter to the MPEG2 Stream input pin of the mpeg2 demux. I don't get any errors, just nothing happens. If I 'break' in debug and connect to the remote graph I can, however, render the capture filter mpeg2 TS output pin using Graphedit and it happily hooks up with the mpeg2 demux.

I know this is all a bit vague but what I'm asking is...is there anything special about the default MPEG2 Demux that means I have to treat it differently? I'm specifying the pin media type/subtype/format by name or GUID as shown in filter properties in Graphedit.

There's something I want to record on Boxing Day but it's no big deal, I could always record from my STB to VCR or even just run the graph manually in graphedit.

You'd think I'd find something better to do on Christmas Eve than programming wouldn't you? Sad, sad man.

Cheers,
Brian

GB-PVR supports DVB radio recording fine for me... just use TMPGEnc (or GraphEdit) to demux out the MP2 audio from the resulting MPG file (An app which runs post-recording, to detect if MPG files have no video stream, and automatically demux the audio (and perhaps auto transcode to MP3) would be useful).

Is this the first DVB app you've written using DirectShow? I managed to get a successful graph working eventually - my app has the basics in place for saving DVB EPG to XMLTV format - this got abandoned when Sub integrated this into GBPVR! It's very tricky to get a successful graph working though...

funkybro

[bgowland]

GB-PVR supports DVB radio recording fine for me... just use TMPGEnc (or GraphEdit) to demux out the MP2 audio from the resulting MPG file (An app which runs post-recording, to detect if MPG files have no video stream, and automatically demux the audio (and perhaps auto transcode to MP3) would be useful).

Interesting idea although the few times I've tried it, I ended up with a 0KB size file. Then again, I use DVR-MS as my recording format in GB-PVR - I gave up on trying to use the other muxes. The Cyberlink one was most stable but occasionally crashed the recording service. Maybe the DVR-MS file writer doesn't like it if there isn't a video component. In saying that though, if I 'watch' a DVB-T radio channel on my Freeview box, there IS a picture albeit a 'still' one so I don't understand why GB-PVR doesn't record it.

Is this the first DVB app you've written using DirectShow?

Yes. The first attempt to do any graph building programmatically, in fact. I was pretty pleased with myself when I managed to get the DVB filters hooked up with very little effort - the problem with the MPEG-2 Demultiplexer filter still eludes me. For the life of me, I still don't understand what I'm doing wrong.

No matter - it was just something I was playing with. I could probably find the solution if I had enough time to plough through the numerous sample files that are around. As ever, I have about half a dozen programs on the go at the same time - one of these days I'll learn to concentrate on one at a time.

Cheers,
Brian

[funkybro_uk]

Interesting idea although the few times I've tried it, I ended up with a 0KB size file. Then again, I use DVR-MS as my recording format in GB-PVR - I gave up on trying to use the other muxes. The Cyberlink one was most stable but occasionally crashed the recording service. Maybe the DVR-MS file writer doesn't like it if there isn't a video component. In saying that though, if I 'watch' a DVB-T radio channel on my Freeview box, there IS a picture albeit a 'still' one so I don't understand why GB-PVR doesn't record it.

The bad old days of worrying about muxes and 0KB recordings ended for me on the day I installed Cyberlink mux 5.0.0.1307. The un-muxed MPG files won't play for me at all on Media Player/Winamp or anything, don't know what's wrong with them...

Yes. The first attempt to do any graph building programmatically, in fact. I was pretty pleased with myself when I managed to get the DVB filters hooked up with very little effort - the problem with the MPEG-2 Demultiplexer filter still eludes me. For the life of me, I still don't understand what I'm doing wrong.

I had similar problems when trying to do the same thing - I did it in C++ using the source code of a channel scanning app I found elsewhere as the basis. IIRC you need to do some initialization on the DVB-T network provider (e.g. tuning it in or something) before you can connect it to the demux filter. I'll hunt out my old app tomorrow and see exactly what I did.

I too have been looking at the DirectShow .NET stuff on sourceforge - it seems to cut out a lot of the code involved when using C++ (much of which is meaningless to me as I don't know COM at all) - but having a working graph would be a great basis for future work.

No matter - it was just something I was playing with. I could probably find the solution if I had enough time to plough through the numerous sample files that are around. As ever, I have about half a dozen programs on the go at the same time - one of these days I'll learn to concentrate on one at a time.

Likewise! Got so many things on the go, but none actually likely to be finished any time soon!

funkybro