Recording audio files from Freeview/Freesat radio stations

[bitoclass]

I suspect I am the only person in the world with a 2002 Modular Technologies DAB PCI card running under Windows 10 and recording various radio programmes, but it only has 32-bit drivers so I'm looking to move to using NextPVR for my radio recordings instead so I can upgrade at last to 64-bit Windows.

So I've started to try using NPVR to record from DVB-T/DVB-S radio channels that I have tuned and in my EPG. And it does record, but the resulting .ts file sizes are enormous.

Looking at the file properties, it seems the file is a bit confused about its contents. An example is a 1hr recording which is as follows:

The file size is 778MB.
The Details of the file when I view Properties in Windows file explorer show Video info with no frame width or height but a data rate of 1592kbps, and total bitrate of 1784kbps; and an Audio bit rate of 192kbps.
When I play it in Windows Media Player and open the file info from there it doesn't mention video content at all and just shows the 192kbps of audio.

To my mind the recording file should therefore be 192×60×60÷8÷1024 = 84MB, but because it's keeping 1.5Mbps space for video content that doesn't exist, it's making a file nearly ten times as big.

Is there a way to address this? Can I ask NPVR to record in an audio-only format for selected scheduled recordings, or flag selected channels up as being audio-only so it doesn't keep space for video in recordings?

Thanks!

[sub]

If you can do a short recording, and put it somewhere I can download from, I'll check it out.

In general NextPVR records all the streams the broadcaster includes with a channel. Those can be all sorts of things, like subtitles, data services etc.

[bitoclass]

Thank you! There's a file here which is one minute of BBC 6 Music, which is 160kbps so I think should be just under 1.2MB in size if it only contained the audio, but the file is in fact 12.4MB in size and again Windows claims it has a video data rate of 1566kbps. Thank you for your help!

https://onedrive.live.com/redir?resid=6B...=file%2cts

[mvallevand]

They don't seem enormous compared to video. Why need just remux shows you want to keep and remove the extraneous streams/

Martin

[bitoclass]

They don't seem enormous compared to video. Why need just remux shows you want to keep and remove the extraneous streams/

Thanks, but I'm trying to replace a DAB-based system that records about 15 radio shows a week and just gives me an .mp2 file to copy straight onto a mobile device to listen to on the go etc. - I don't really want to have to do anything complicated so often, although if there's a way to automate it as part of a post-recording script or something I guess I could consider doing that...

I'd just rather there was a way for audio-only channels to be captured into recording files that only contain the audio data transmitted rather than a sort of phantom empty video stream taking up 90% of each file and thereby making each recording take ten times as long to copy to a device or upload to Dropbox etc.

And of course this would come with the added bonus that the sound quality is a lot better on DVB than DAB

[gEd]

fyi: whenever I record and radio shows, I just use MCEBuddy to monitor that specific folder (eg: R:\recordings\The News Quiz) and convert the .ts files to .mp3 to copy onto my ipod to listen to in the car.

[bitoclass]

fyi: whenever I record and radio shows, I just use MCEBuddy to monitor that specific folder (eg: R:\recordings\The News Quiz) and convert the .ts files to .mp3 to copy onto my ipod to listen to in the car.

Ooh, that definitely sounds like an option worth exploring – thank you!

Still slightly bemused by the file sizes and liked the idea of being able to rely on NPVR to manage numbers of recordings kept etc, but if I can get something similar to gEd in place I think I'd be no worse off than I am with my ancient DAB card, anyway

[sub]

I looked at the sample file. There is no video stream in there, but bbc has included a pile of extra data streams. NextPVR always records everything about a channel, so you ended up with a recording that has these extra BBC data streams.

Honestly, its probably not worth me doing anything about it directly in NextPVR. As gEd suggestion, you could easily use something liek MCEBuddy or ffmpeg to convert the file to a .mp3 or simliar.

[bitoclass]

Thanks for checking the file, much appreciated. I'm investigating ffmpeg and MCEBuddy now.

[bitoclass]

In case anyone else stumbles across this thread with similar needs: I've got this working rather nicely now using ffmpeg to extract only the audio stream from the recording, and I've included a line to delete the original recording then too. My 'PostProcessing.bat' (and 'PostCancel.bat') file is pasted below. It relies on me having all radio stations in the 700-799 channel number range (and of course the installation path of ffmpeg being as shown):

Code:

Set FILENAME=%1
Set CH_NUM=%2
Set REC_TITLE=%5

For %%A in (%FILENAME%) do (
    Set FOLDER=%%~dpA
    Set NAME=%%~nxA
)

IF %CH_NUM% GEQ 700 IF %CH_NUM% LEQ 799 (
    Call C:\Progs\ffmpeg\bin\ffmpeg -i %FILENAME% -codec:a copy "%FOLDER%\%NAME%.mp2"
    del %FILENAME%
)