The sound-quality of DRM transmissions

[drmdab]

We had a very nice (but short) discussion in the theard about The Disco Palace's (http://www.drmrx.org/forum/showthread.php?t=2184) new DRM transmission regarding the sound-quality of DRM broadcasts. I think we could continue discussing here.

I have listened to some recorded DRM broadcasts now and have to admit that The Disco Palace's sound-quality maybe one of the best. I decided to upload some sample records and self-made files to the forum. Currently I am not able to use my DRM receiver so most of the files are a little bit older.


1) Sample self-made (http://www.dxaktuell.de/drmsound/DRM-STEREO-SRCoff.mp3): 22.14 kbps UEP (22.0%) AAC+ P-Stereo and SRC Off
2) Sample self-made (http://www.dxaktuell.de/drmsound/DRM-STEREO-SRCon.mp3): 22.14 kbps UEP (22.0%) AAC+ P-Stereo and SRC On
3) Sample self-made (http://www.dxaktuell.de/drmsound/original.mp3): Original


4) BNR Digital (http://www.dxaktuell.de/drmsound/bnrdigital.mp3): 26.56 kbps AAC+ Mono - Not bad in my opinion, not many audio artefacts
5) Radio Prague (http://www.dxaktuell.de/drmsound/radioprague.mp3): 18.44 kbps AAC+ Mono - Worst sounding example here
6) VoA IBB (http://www.dxaktuell.de/drmsound/voa.mp3): 14.76 kbps AAC+ Mono - Quite good for 14.76 kbps, noticed some audio-artefacts (news-announcer)

What do you think about these samples? Do you have files which show the best sound-quality in your oppinion?

[simone]

What is the meaning of SRC?
Simone

[drmdab]

That's high quality sample rate conversion. I wasn't sure if this would cause any big difference in the sound-quality and Spark encoding so decided to make two seperate files for sure - why not.

[lmaes]

I tried to listen to the sound files, but they seem no longer available.

Now that The Disco Palace is in real stereo, it would be nice to have a recording from your place, so that the quality can be compared to the other stations.

Would love any comment.


Ludo

[lmaes]

Links to the soundfiles have been restored, so we had a chance to listen to them.

Your observations are correct, so it would be nice to compare them to the sound of The Disco Palace.

I guess the big difference will be the presence or absence of stereo. We believe that for music in the 21st Century, it should be stereo at least, so that a comparison to FM or internet radio can be made.

If we can achieve that DRM is comparable to FM stereo or internet radio at 128 kbps, then commercial broadcasters might be interested to consider DRM as a platform to distribute their pograms, knowing the other advantages that DRM offers like for example large coverage area.

Ludo

[Brendan1]

Ludo - I'll try and record a segment of DP for you this weekend if you would like. That way you will have some "on the ground" proof of quality!

Let me know, okay?

[lmaes]

Ludo - I'll try and record a segment of DP for you this weekend if you would like. That way you will have some "on the ground" proof of quality!

Let me know, okay?

Dear Brendan,


I would like that very much and in case you can attach it in this thread, we can all compare.


Ludo

[Brendan1]

Ludo - Great, I'll try to record some tomorrow, but I won't be able to post it until Saturday at some time due to other commitments later in the day after the transmission.

It will probably be in a ZIP file format, since that looks to be the only way to post audio here on the forum.

[simone]

A comparison of music channels and international news broadcasters is hard to do, I think it is better to compare stations with similar content and aims.
Also I think the example from Radio Prague above had a technical problem and is not a typical example of the chosen settings.
So I have uploaded a recording from The Disco Palace and one from RTL (MF mode B, 9kHz) here (http://www.stoepplernet.de/drm/audioquality_rec/), besides the slighly lower bitrate and audio bandwidth from RTL, and higher audio levels from The Disco Palace the main difference is the much higher dynamic range of The Disco Palce:

.........The Disco Palace..... RTL
Min value L: -69.00%.... -41.37%
Min value R: -60.53% ... -34.99%
Max value L: 82.10%..... 37.92%
Max value R: 76.58%..... 35.25%


@Brendan: If you have problems uploading your recordings here, you can email me your files.

Simone

[Brendan1]

@ Simone: Thanks, I will do that. Even 30 seconds comes to 657 kb as an MP3, and I couldn't figure out how to get it smaller (=100kb).

I'll send you my samples shortly.

[simone]

Thanks, I have uploaded your samples too, same link (http://www.stoepplernet.de/drm/audioquality_rec/), in the folder "from Brendan",
Simone