Manipulating Radio Recordings

Black Hole said:
So the output is not genuine MP3?
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An MP3 is no different to an AVI, MKV, or lots of other formats in that it can come in many varieties. The ones that I have extracted from TS files were 256kB/s, although this is not the most common bit rate anything from 32 to 320 kbit/s (and more) is allowable with sampling frequencies of 32, 44.1 and 48 KHz. Not everything plays all varieties, But they are still genuine MP3s
 
All MP3 players should play MPEG1 layer 2 (MP2) files but sometimes you need to 'fool' them by calling the files .mp3 instead. The iPod doesn't - a typical case of Apple's shoddy "Not Invented Here" attitude.

At the moment it looks like I need to import the files to iTunes, select them, convert them to AAC, remove them all again, delete/move the mp3 files from the music directory and reimport the m4a files that were created during the AAC conversion. What a load of faff! (Yes you can see which file is which using info, but there are 650 of them and it'll be faster this way!)
 
Sam Widges said:
All MP3 players should play MPEG1 layer 2 (MP2) files but sometimes you need to 'fool' them by calling the files .mp3 instead. The iPod doesn't - a typical case of Apple's shoddy "Not Invented Here" attitude.

At the moment it looks like I need to import the files to iTunes, select them, convert them to AAC, remove them all again, delete/move the mp3 files from the music directory and reimport the m4a files that were created during the AAC conversion. What a load of faff! (Yes you can see which file is which using info, but there are 650 of them and it'll be faster this way!)
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It should be possible to run ffmpeg from a fast machine against the files on the Humax (Samba share perhaps) to convert them en-mass.. I'll have a play later. Best case would be that it's just a container attribute that iTunes doesn't like.

iTunes definitely plays the generated mp3 files, or it has done for the ones I've extracted to mp3 - I hadn't tried to put them onto an iDevice though.
 
iTunes plays them fine, but they won't transfer onto an iPod. I know you could use ffmpeg, but this seems like an Apple-only problem and I think that it's better to use iTunes for the conversion as iPod owners will already have that installed.
 
If you extract the audio with -acodec libmp3lame instead of -acodec copy then it produces a file that works fine on an iPod, but it's impractical to run that on the Humax as it doesn't have the horsepower.

Batch conversion of the copy extracted mp3 files is easy enough with ffmpeg on another box though.

There might still be a way to produce iPod compatible files without having to transcode, I'm going to play with different container types.
 
I've updated the webif-driven audio extraction so that it automatically adds ID3 tags to the generated MP3 file based on the original programme information, provided you install the optional id3v2 package. @Sam - You could do the same with your batch converter.

id3.png
 
I recorded a radio programme yesterday and was trying to convert it to mp3. It did work after a fashion, but the file (mp3) would only play in VLC. I tried SplashPlayer and WMP but they both did nothing.

I have ffmpeg installed.

Initially, I simply right clicked on the radio.ts file and downloaded it to my PC. That resulted in an mp2 file and would play in Splash Player without a problem.

As an experiment I then clicked on the extract audio option. The file was downloaded to my PC as an mp3, but as I say, will only play in VLC. This is no longer my player of choice and I like to use SplashPlayer and ultimately copy the file to my iPhone.

Have I missed a trick or is the more usual user mis-op?

Thanks.
 
That's strange. I've managed to play the generated mp3 files in iTunes, Buzz, VLC and the Humax MP3 player. I think there is something about the way I'm constructing the mp3 wrapper that is confusing Splash and also causing iTunes to refuse to put it onto an iP* - the underlying audio stream is obviously ok so I'm hopeful there is a way of wrapping that up that will keep everything happy - the alternative is that we'd have to transcode it which is too much for the little Humax.
 
Unfortunately my new car stereo is another device that is not happy with the "MP3" created by this process.

Reading back through this topic, EP says MP2 is a video format, and yet Wikipedia says MPEG-1 layer II and MPEG-2 layer II is MP2:
Ezra Pound said:
MP2 is a video format not an audio format, MP1 and MP2 Video both contain MP3 (correct title is MP1 Layer3), The radio TS format is an Empty MP2 video file with MP1 layer 3 Audio
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http://en.wikipedia.org/wiki/MPEG-1_Audio_Layer_II said:
MPEG-1 Audio Layer II or MPEG-2 Audio Layer II (MP2, sometimes incorrectly called Musicam or MUSICAM) is a lossy audio compression format defined by ISO/IEC 11172-3 alongside MPEG-1 Audio Layer I and MPEG-1 Audio Layer III (MP3). While MP3 is much more popular for PC and Internet applications, MP2 remains a dominant standard for audio broadcasting.
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I have yet to find out what the difference between MPEG-1 and MPEG-2 is.

Is .mp2 a valid file type? If so, and if the end product of the WebIF "extract audio" process is better described as MP2 rather than MP3, wouldn't it be better that the file is given a .mp2 extension?
 
I'm not sure if you found the answer to your question, Black Hole (I see this is an old post). However, in case not: an MP2 file is a valid audio file type and is found in .mxf files , which are essentially wrappers that hold essence (audio and video files) and metadata (technical and descriptive) and are found in broadcast TV scenarios. I've not come across mp2 files in non-broadcast TV workflows.

MPEG 1 is a standard for lossy compressed video files and the mp3 audio compression format was derived as part of that. MPEG 2 was developed from MPEG 1 and is used in digital television scenarios, although the later mp4 (ptII) format has taken its place in some situations
 
Things have moved on a bit since then. There is now an option in the WebIF to force the extract to MP3 operation to produce proper MP3 (but it takes a long time).
 
Devaprem said:
I'm not sure if you found the answer to your question, Black Hole (I see this is an old post). However, in case not: an MP2 file is a valid audio file type and is found in .mxf files , which are essentially wrappers that hold essence (audio and video files) and metadata (technical and descriptive) and are found in broadcast TV scenarios. I've not come across mp2 files in non-broadcast TV workflows.

MPEG 1 is a standard for lossy compressed video files and the mp3 audio compression format was derived as part of that. MPEG 2 was developed from MPEG 1 and is used in digital television scenarios, although the later mp4 (ptII) format has taken its place in some situations
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MP2 is mpeg1 layer 2 and is the audio compression codec used by pretty well all Digital SD TV (satellite and terrestrial). It's the audio codec found in the SD transport stream (.ts) container files from Humax along with mpeg2 video.

https://en.wikipedia.org/wiki/MPEG-1_Audio_Layer_II

mp4 is itself a container and may or may not have mpeg 4 compressed video contained in it.

https://en.wikipedia.org/wiki/Comparison_of_video_container_formats
 
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Devaprem said:
Interesting - where in the WebIF do I find this? I'm running version 1.2.8-4
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Screen capture on the WiKi HERE, you need Main Menu >> Browse Media Files >> click on file >> Extract Audio. The Setup for different MP3 layers is at :- Main Menu >> Settings >> General Settings >> Audio Extraction Type
mp3.jpg
 
I now use tsMuxer to extract the native .mpa audio stream from my Freesat radio recordings. Faster than converting to .mp3 which I was also finding to have a problem gradually losing sync of the resume point when Play/Pausing when used on a long (three hour) recording on my Rockboxed Sansa Clip+ PMP.
 
Devaprem said:
Thanks. Just tested and working but slow, as people have said
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It doesn't matter how long it takes if you have the patience to just let it get on with it in its own time (and leave the box turned on). You can configure things to automatically process radio recordings, so all you have to do is pick up the results later.
 
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