Converting MP2 to MP3

[twharrison]

The following comments are with reference to earlier threads concerning MP2 format files.

Recently I acquired a PC TV card that allows recording directly to a PC’s HD in either MPG for video+audio or MP2 format for just audio streams. Both types of file have been recorded and played back via the software that shipped with the TV card (Nebula DgiTV). As I understand it, when recording, the decoded digital stream is fed directly to disc and does not go through any kind of DAC. The resultant file should therefore be as transmitted although I have noticed differences between Freeview radio stations. For instance BBC R1 / R2 /R3 are transmitted at 192Kbps whereas BBC R6 is only 160Kbps – both are sampled at 48KHz.

Playback through dBpowerAMP is less successful and the audio is fast (someone described it earlier as ‘chipmunk style’) and is full of clicks, pops and whistles. Both the bit rate and sample rate are reported correctly but I suppose this comes from the ID tag.

When attempting to convert the MP2 file with dMC the process runs for approximately 5 seconds before stopping and reporting it as completed. The output MP3 file is a few seconds long and is too short to ascertain if its quality is OK. I have also tried converting to WAV with similar results.

The latest version of dMC has been installed (dMC-r11b3).

Any help would be appreciated.

[xoas]

Re: Converting MP2 to MP3

Have you tried enabling Professional Frequency Conversion?
(Go Start>All Programs>dBpowerAMP Music Converter>Configuration>dMC Configuration-there is a box to check to enable Professional Frequency Conversion and the default setting for this is unchecked (off)).
Best wishes,
Bill Mikkelsen

[twharrison]

Re: Converting MP2 to MP3

Bill,

Thanks for the info.

Professional frequency conversion was already checked so I tried converting the file with it unchecked but it made no detectable difference.

Tim

[ChristinaS]

Re: Converting MP2 to MP3

Bill,

Thanks for the info.

Professional frequency conversion was already checked so I tried converting the file with it unchecked but it made no detectable difference.

Tim

Have you also installed all the latest versions of the requierd codecs?

[xoas]

Re: Converting MP2 to MP3

Playback through dBpowerAMP is less successful and the audio is fast (someone described it earlier as ‘chipmunk style’) and is full of clicks, pops and whistles

I take it you are playing through dBpowerAMP Audio Player (or dAP). If so, are you using the dAP r3 beta version? As this has the new MAD decoder it might give you better playback of these files than dAP r2. This might concievably help with your other problem as well.
The other thing you could try is installing the MP3 Lame .EXE codec which allows you access to other mp3 encoding options which the regular Lame codec does not allow access to.
Finally, with respect to the playback issue again you might want to consider the following which is posted as a FAQ for dAP:

http://forum.dbpoweramp.com/showthread.php?t=4619

Keep us posted on how you make out.
Best wishes,
Bill Mikkelsen

[twharrison]

Re: Converting MP2 to MP3

Thanks for all the suggestions.

Playback: I have now tried the dAP R3 version - it plays the MP2 file (192kbs / 48kHz) but there are bleeps and whistles and other other intrusive noise.

Converting: Downloaded and installed the MP3 Lame.EXE codec. This did convert the MP2 file (192kbs / 48kHz) to an MP3 file (192kbs / 48kHz) but the MP3 file plays back with the beeps and whistles. It was an improvement but still did not produce a satisfactory result.

Where can I find information about passing instructions through the command line when executing MP3Lame.EXE ?

dMC will not recognise my MP2 files (160kbs / 48kHz)!

I am beggining to suspect the BBC transmit their digital output with some kind of copyrite protection although this does not explain why I can playback the files though the player that came with the Nebula DigiTV USB card (for those interested this is quite a good product).

[twharrison]

Re: Converting MP2 to MP3

I've answered my command line query - I just found the CLI instructions (lesson: read first THEN ask the questions).

Tim

[twharrison]

Re: Converting MP2 to MP3

I give up - what instructions can be passed through the command line and how is this achieved?

Is there a list some where with examples of syntax etc.?

Tim

[xoas]

Re: Converting MP2 to MP3

Tim-
I am going to assume that the bleeps, whistles and other intrusive noise on your converted mp3 file were pretty much the same stuff you were getting back when you were playing the mp2 file on dAP. And it sound like you were able to remedy the fast audio playback. If these assumptions are sound, then I think that we have one part of your problem nailed down (the actual mp2 to mp3 conversion). That would leave the question/problem of how to access/play back the mp2 files without the noise.
Am I right in assuming that you do have a means of playing these mp2 files without the bleeps/whistles/noise (say thrugh the software that came with the card)?
If so, I can think of a few things you might try.
First, you should be able to record your mp2 files off of the soundcard as they play (using the program that came with the card) using dMC Auxilary Input. Admittedly, if you have many files this might be a bit tedious.
Second, I would consider the possibility that the extraneous noise might be a result of too much gain in the files. If you have the Power Pack, do you have the volume normalization dsp enabled? If so, turn it off and see if that makes any difference. If it helps only a little, try enabling the Volume Quieten dsp from the Power Pack. Try both of these first with dAP to see if that affects playback and then with doing a conversion to through dMC.
Also, I wonder about whther you might have more than 2 channels of audio in your source files and about whether you might not get better results converting your 48khz mp2 files to 44k mp3.
You may want to contact the Nebula DigiTV site to ask for support on the possible causes for these issues as I would assume that they are more familiar with such issues as whether your files might have digital rights protection safeguards or whether there may be some other compatibility issues or signal processing issues that might arise if you try to listen to or convert your files with some other program.

Finally, when you say that dMC will not recognize your mp2 files, what do you mean? Since you have been able to convert with dMC (however poorly) it seems unlikely that you mean you cannot access them at all. Could you provide a bit more information about what you mean, and perhaps some information about what you have done to access the mp2 files for conversion?

Best wishes. Keep us posted on your progress.
Bill Mikkelsen

[Unregistered]

Re: Converting MP2 to MP3

Hi

I'm new here - so: thank you for the great program (dMC)!

Like the author of the thread I use a DVB-card (Pinnacle PCTVSat) for recordings of radio plays (for instance BBC 7). The software of the card gives me the original Transport Stream (TS) which I demux with PVAInstrumento (another great one). I don't know the Nebula software - perhaps it has some problems with errors in the Transport Stream. PVAInstrumento might give you a better result.
And: BBC Radio channels are not encrypted!

Now - after recording and demuxing I have mp2-Files (MPEG Audio Layer 2) with bitrates between 160 and 256 kbps and a sampling rate of 48 khz (DVB-Standard).

Without dMC I wouldn't have so much fun because my standalone (MP3) and portable (MP3 and WMA) players don't support MP2-Files. So I have to transcode.

My questions/suggestions:
Since my portable player needs 44.1 khz SR I have to downsample. Using the Professional Frequency Conversion option ist quiet a hard hitter on the performance. Transcoding speed is only 30% of the rate without the option. I looked at the ssrc.exe and it has an option for "fast" conversion. Perhaps this option can be implemented in dMC. I don't know what algorithm uses madplay.exe for downsampling - but it is quiet a bit faster than ssrc - perhaps a second option for selecting a resampling method? And: please position the "selection of resampling method: windows/madplay/ssrc fast/ssrc precision" in the main conversion window.
Is it possible that the dMC conversion window closes itself after conversion of file(s) - like an "end program after completion"-option?

I'm sure that ever more people will record digitally (per satellite or cable or terrestrial) broadcasted radio programs. Since the DVB-Standard defines for Audio Mpeg Layer 2 with 48 khz SR as standard there will be a growing interest for "quality and speedy" conversion from MP2/MPA to formats which are supported by standalone and portable players.

Thanks