Hi,
I am in the habit of recording bbc r3 broadcasts digitally, especially live gigs. (Hauppauge dec 2000-t Freeview STB via USB). For some months now I have noticed distortion on the resulting mp2 files which I didn't use to get. The attached sample is fairly extreme, but is a good example.

I have been tearing my hair out with Hauppauge firmware/application upgrades, winamp mp3 plugin alternatives, but can't seem to find a way to avoid it.

It seems to be just this year - does anybody know if the beeb is doing something different/wrong? Or what this type of distortion is caused by? The wife says it sounds like the speaker has a sore throat. It is a lot more disturbing if it is a solo piano or similar.

All contributions gratefully received.
Guy

Are you recording from an analogue radio? Does R3 broadcast digitally? Are you capturing the BBC stream from the Internet?

He said it is from freeview = dvb-t = digital.

Correct - the file uploaded should be exactly what was broadcast. The question is: does the bad quality originate with bbc encoding, or is there a problem with my set top box and it's stream ripping?

Do people agree that it shouldn't sound like this?

Guy

PS I did use PVAstrumento to clean up the mp2 file - it was even worse before that.

Firstly, I've listened to the sample, and it sounds perfectly normal to me. But it's hard to tell with such a short voice-only sample.

Secondly, there is nothing you can do with your software to improve the quality. As you say, you are capturing the original broadcast MP2 bitstream - either your software works (and you get an MP2 file that plays without errors), or it doesn't. The quality of the stream is totally dependent on the BBC.

I'm also confused when you say that pvastrumento improved the quality of the recording. The only change pvastrumento will make to your stream is to repair errors due to missing data. i.e. if your reception isn't 100% perfect, it will drop any partial frames to create a legal MP2 stream - but it won't alter the content of any frames.

Maybe the problem is with your MP2 player on your PC - try using a completely alternate player, such as foobar2000.

This all assumes that there is no re-encoding of the stream being done by any of your software. There shouldn't be, but you never know.

If you still have copies of any old R3 broadcasts, do you also have problems playing those back?

Dave.

guysivey,

I agree - the sound of that is horrible. Radio 3 usually sounds very clean and clear. Is it just this broadcast (and this microphone/presenter) or is it a more general problem?

The file you have provided sounds transcoded. It's been shown that the BBC Radio 3 broadcasts on Freeview aren't quite as high quality as those on DAB (when the bitrate is 192kbps on both) - either the BBC are using a poorer encoder for Freeview, or there is something else in the chain degrading the quality.

http://www.hydrogenaudio.org/forums/index....showtopic=24041

However, the previously noted difference is quite subtle, whereas the sample you have provided just sounds horrid to me!


There is an issue with decoding some mp2s from Freeview (depending how they were captured) - the Winamp mp3pro decoder (and maybe some others) chokes on them - but I'm using Foobar2k under XP with an audiophile 2496 sound card, so I believe what I'm hearing is exactly what is in your file.

So, either Radio 3 on Freeview has got even worse, but you're the only person who has noticed (quite possible - I'll take a listen tonight if I get chance) - or your software has started transcoding where previously it didn't - or there's just this one radio programme that comes from a poorer quality source, and you keep recording it! Having noticed the very poor quality on this source, you're now listening to the rest of the output and noticing the slight problem which you never noticed before.

As you're probably aware, being in the UK and having the option of buying low bitrate DAB digital radio as endlessly promoted on the BBC, the "word's finest public service broadcaster" aren't exactly being careful with technical quality in digital broadcasts, but if they are making things even worse yet again then someone should point it out. Let's get some confirmation first though - it could be something wrong your end.

Which programme, at what time, did that short extract come from?

Can you post an extract from a programme which you feel doesn't sound as bad, and let us know if you think there's still a problem with that?

Hope this helps.

Cheers,
David.

I've just made two simultaneous recordings from Radio 3 - the DVB-T (Freeview) version and DVB-S (Satellite) version.

I've used my own Linux software to make these recordings, so can say with 100% certainty that these are the original MP2 bitstreams as broadcast by the BBC.

This message contains the DVB-S recording, the next will include the DVB-T.

EDIT: One thing to notice is that the DVB-S is joint-stereo, but the DVB-T is discrete stereo. But I think this has been the case for a couple of years.

Also, just for the record, the DVB-T is from the Crystal Palace transmitter.

Dave.

The same (approximately) period in time, but this time DVB-T.

Dave.

For non UK users, could you please clarify which one is DVB-T and which one is DVB-S?
I thought DAB was DVB-T and Freeview was DVB-S, but I am now confused.

sure, I have plenty of samples of varying degrees of horridness. I'll put up some more and longer ones tonight.
Guy

DAB is "Digital Audio Broadcasting". It's a terrestrial broadcast system for radio - intended to replace FM.

DVB is "Digital Video Broadcasting". It comes in three flavours - DVB-T (terrestrial), DVB-S (satellite) and DVB-C (cable). It can carry both TV and Radio services.

In the UK, the DVB-T service is known by the marketing name "Freeview". The DVB-S service is marketed as "Sky Digital".

All these platforms use MP2 compression.

Dave.

Thank for the clarifications. I thought that "Freeview" was a satellite service (it really sounds like a commercial marketing name)

I think all the mp2 streams uploaded here sound awful. Surely 192kbps MP2 can sound better than that?

The ones from DaveChapman sound like broadcasts of a mono LP record.

(though I've only downloaded the first one as I type).

Dave - would it be possible for you to try again when they're broadcasting higher quality source material?

Cheers,
David.

ROTFLMAO

(you're in the UK - you know what I'm laughing at - and it's not you!)

Cheers,
David.

Here's another pair of samples recorded from the BBC's "Afternoon Performance". I recorded both DVB-T and DVB-S, again for 30 seconds.

Dave.

Well, I don't know what kind of source material BBC used for this, but for 192 kbps this sounds really bad....

I'm also unhappy with the sound quality of FreeView. The other day I checked the transmitted bitrate by capturing the original bitstream with Nebula Electronics DigiTV USB. Here's the bitrate table I created for all DVB-T TV broadcasts excluding radio broadcasts (the bitrate table is at the bottom of my Japanese diary; the bitrate depends on the program or date/time):
http://nyaochi.sakura.ne.jp/xoops/modules/...index.php?p=130

BBC ONE, TWO, and THREE use MP2 48kHz 256Kbps and other MP2 48kHz 192Kbps. The sound quality of BBC ONE, TWO, and THREE is on the borderline for me. On the other hand, I often hear the annoying sound from the other broadcasts without my concentration, for example, while watching a music video transmitted by The HITS and TMF. The sound quality of the radio broadcasts (not DAB radio) is much worse: I don't remember the exact figure but they seem to use MP2 48kHz 128Kbps or lower and can't stand the quality.

I've never listened to the DAB radio stations before, but had an illusion from ad (they claim pure clear sound!) that DAB digital radio uses much higher bitrate or other audio formats. But do they have only the same quality as TV broadcasts? Why don't they care about the sound quality while the video stream has a good enough quality?

EDIT: But I like FreeView because the transmitted stream has no DRM. Japanese DVB-T stream has build-in copy-once protection, which makes us very annoying and unhappy.

Hello David,

Herewith some more samples. Dates exact, times approx. You will see that some are worse than others. You have to listen quite close on "Voice" to hear the effect, but it is quite pronounced on Taj and Murray. Even then it isn't continuous - just at certain moments. The sample I posted before (Surman) was from the same broadcast as the one in this batch called "Mccoy". All are live broadcasts or sessions engineered entirely by the BBC!

I can accept there is a problem with my capture (this device has a bit of a reputation), I would just like to know so I can concentrate on it. It is a pig to experiment with. BTW I captured some low bit rate non-BBC transmissions, as research, which sound ok! Could post one if interested.

I have had mp2 files from Freeview via my USB STB which have been unplayable, or very clicky until they were cleaned up by PVAStrumento. Confirmed by Hauppauge forum. It's only recently (this year?) that I have noticed this problem. I am not sure about the quality depending only on the beeb, because I'm a bit suspicious about the device I'm using. I would like to rule out the beeb b4 getting serious with my box.

It made a big difference, as mentioned above. Got rid of lots of clicks.

Tried iTunes, Foobar, WMP, Winamp with in_mpg123.dll, mp3directcut. Same problem.

Or not quite capturing 100% of the whole stream? Or modifying it in some way? This is what I am wondering. As mentioned Hauppauge/Technotrend software and firmware have been a bit flaky in the past.

I still listen to lots of old broadcasts some of which have excellent quality. I feel it was about the beginning of this year when it started to notice it.
Cheers,
Guy

Dave,
These sound fine to me, although the S version sounds maybe a bit more sibilant. Is that what "S" stands for? But nothing like the grunge behind my samples. I am getting more suspicious of Hauppauge.
Guy

If you want to make a recording of R3 at a specific time this evening, I can do the same thing and then send you my recording (from DVB-T).

Just let me know.

BTW, what transmitter do you receive Freeview from? As I mentioned above, I use Crystal Palace, so there is always the possiblity there is a problem with the BBC's feeds to your transmitter. But Hauppauge seems the more likely culprit.

Dave.

guysivey,

It could be down to your poor reception (or poor hardware or drivers making it seem like you have poor reception). PVAStrumento has to rebuild damaged or missing information - not all of that missing information affects the sound dramatically - some of it affects it subtely, and if the files are absolutely full of errors which are then fixed, that could cause the gravely "broken speaker cone" sound.

When you have small but continuous errors on DAB, this sounds like "boiling mud" - a near constant gurgling and grinding kind of sound in the background. That's not what you have here, but it's not a million miles away, and may be how it manifests itself on DTT when something goes wrong and is partially fixed.

If it's not that, then I think the mp2 stream is being transcoded somewhere.

But try what Dave suggested to verify - the BBC UK-wide radio stations are encoded in London, so you should receive exactly the same thing whatever your transmitter.

Cheers,
David.

P.S. IIRC BBC Radios 1-4 are on the 64QAM SDN mux, which is harder to receive than all the other BBC broadcasts on their own 16QAM muxes.

They sound very wobbly, and I'm not convinced it's the performance. Could be anything - dodgy tape, dodgy codec, or maybe "interesting" singing.

And yes, the HF sounds strange too.

I assume you're interested in this Dave to have set up both DVB-T and -S reception - what's your overall opinion? Does one usually sound better than the other?

Cheers,
David.

Thanks for suggestions, David.
I am veering towards the poor hardware/drivers, although what bugs me is that they used to be ok, before I went through one level of s/w upgrade too many.

I have arranged with Dave to make recordings of the same thing at the same time via 2 different devices. I am also trying to get info from Hauppauge UK.

Will post verdict on the Hauppauge vs BBC debate.

Guy

I normally record all my radio from DVB-S - I haven't done any comparisons with DVB-T.

The reason I bought the DVB-T card was to record the TV channels which are encrypted via satellite (ITV, C4 and C5, and originally the BBC as well).

Dave.

I bought a Hauppauge device so that I had a standalone set top box as well as something which could be connected via USB to my laptop when I felt like recording something. Usually music. But I am reaching the end of my tether with it. I would do better with a cassette recorder. Any other suggestions for a STB/USB device which works?

Guy

Me too - Mee too. I have been wondering why radio 3 was sounding so bad over DTT. I am using a DigiTV card, I finally tried this evening by comparing my DAB radio (Pure tempus 1) plugged into the hifi with the PC plugged into the hifi.

The DAB definitely sounded a lot better, but still nowhere near as good as a CD played through the PC.

This was the radio3 concert at 7:30pm.

I think that the low volume level they use on radio 3 makes it significantly worse. It makes violins in particular sound scratchy and there was also a very definite loss in stereo imagining on DTT compared to DAB.

There were also a couple of times when the piano came in suddenly when the distortion was truly amazing.

I often listen to CD review on Saturday morning and thay has been sounding pretty awful since way before Christmas.

There was a time when music on TV was pretty good - when they broadcast at 256k, but even that seems to have got worse.

I've also tried playing the recorded stream through a couple of different players, by it made no difference - they all sounded the same and awful.

The sound quality is MUCH worse than I get if I lame encode a CD at 192k (although I usually VBR them using r3mix).

I'm receiving (TV at least) from Winter hill.

The problem is definitely not drop out - I first had a psion wavefinder and that did have big reception problems - truly awful piece of kit, and this sounds nothing like the sort of problems I had then.

I think Imight have to go and buy another FM tuner at this rate.

Last night I did what I should have done as soon as I read this thread - listened to BBC Radio 3 via Freeview.

For DTT I have a bog standard Pace OnDigital STB, excellent reception, and a pair of Sennheiser HD 580 headphones. For DAB I have an Evoke-1, again with excellent reception. I don't have any way of getting the mp2 streams into a PC.

I listened to part of "late junction" on Radio 3, and while some of the music sounded OK, the female presenter's voice had very similar distortion to the first sample posted in this thread. This was via DTT. I then plugged my headphones into the Evoke-1, and Radio 3 via DAB was clean and clear and distortion free. I could have been very unlucky, in that the source switched from a re-recording to something live as I changed from DTT to DAB, but since it was the same presenter talking to the same person, this seems very unlikely! The outputs of the DTT box are lower quality than the Evoke-1, but there's not enough of a difference to cause this particular large difference in sound quality.

I _think_ other stations are effected too. At the same time, the 10 O'clock news on Radio 4 sounded horrid on all platforms - an outside broadcast via a lossy link I think - but it sounded worse on DTT than on DAB or FM. I'd swear it never used to be this bad, because I've listened very carefully before. It's amazing that 128kbps J-stereo on DAB sounded better than 192kbps stereo on DTT, but maybe not, given that the source material was mono, and the DAB broadcast uses brand new encoders.

So I think this needs more careful investigation - I could have been imagining things last night (you can hardly ABX two separate receivers in two separate rooms when everyone else in the house is in bed!), but hopefully you'll be able to figure it out with Dave.

Hope this helps - though it might just confuse. I'll ask around and see if anyone else has noticed anything.

Cheers,
David.

David,
Could there be a cunning plot to make DAB sound more acceptable, by making DTT sound worse? Only joking. Quite interested to hear the outcome of your further investigations, because this has been driving me barmy for some months.
Guy

The test programme that Guy and I are both recording is Jazz on 3 tomorrow night (Friday 29 April).

I'm sure it would be very useful if someone with a Wavefinder or similar PC-based DAB receiver could capture the DAB broadcast as well. Does anyone reading this either have one, or know someone with one?

I'll capture both the DVB-S and DVB-T streams, and Guy is capturing his DVB-T stream as well. We are both tuned to Crystal Palace, so it's a good test of his hardware/software.

Dave.

Re DAB radio, I don't know the format used but my radio tells me that the BBC 3 bitrate is still 192k, and most are far lower (especially the "talking" stations).

How are people recording digitally from their set top boxes? Do you need a special kind, or do they usually have a digital out containing the MP2 information? Mine's a cheap little Sony one with only one output (I think) not being used.

Pootle, sorry I didn't see your post before I submitted mine - glad we're all not going mad (well, not in one sense at least!).



I think, while the BBC continue to mess up their digital broadcasts and treat quality like it's a side issue, then getting a good FM tuner and aerial is the best action. This has it's own issues of course, but while more people listen via FM than via all the other platforms put together, and while there is no reason to reduce the quality on FM (compared with DAB, where they are happy to reduce quality to increase the number of stations) it's a good bet - at least on the stations where Optimod dynamic range compression isn't over used.

The worrying thing is that so many programmes are now sent from OB to studio via a lowish bitrate MPEG link, so even the analogue broadcasts have artefacts (not typical on Radio 3 thankfully, but other stations are guilty). Still, even then it sounds better on FM than on other platforms where transcoding drags the quality lower still.

Cheers,
David.

Yes, I've just checked my Evoke-1 DAB radio, and that's showing Radio3 currently broadcasting at 192kbps Stereo.

A very small number of set top boxes (mainly from computer companies like Hauppauge) have USB connections to record the transmitted streams on a PC. "Normal" set top boxes don't give you any way to access the original MP2 streams.

More common are standalone receiver cards for your PC (either internal or USB). Simply put, you plug the aerial directly into your PC and the PC does the work of the set top box.

I have no affiliations, but I did notice today that Scan are currently selling the Hauppauge DEC-1000T USB receiver for 22 pounds: This also has a SCART connector to connect to a TV:

http://www.scan.co.uk/todayonly/

But given Guy's problems with Hauppauge, I'm not sure if it is recommended - I don't own one, but for 22 pounds, may give it a try.

Dave.

This has got absolutely nothing do with the DEC2000-t. All the DEC2000-t is doing is saving the stream to disk - i.e. no recompression is being done. Additionally if it was corrupting the stream it would result in either a) nothing or b) blips and squeaks. It wouldn't result in distortion or poor low/high frequency.

I'd suspect that the level is set to high at the encoding stage (i.e. at the BBC). If you have your sound card's mixer turned up it is very likely that you will get clipping. Have a listen to one of the Emap stations which definately do clip and they sound awful.

But this is certainly not a Hauppauge problem. If you don't believe me, buy any other DVB-T device and you will get equally poor sound quality.

I really hope you're right, CX, because I have tried every kind of reinstall/upgrade I can think of with this device.

It was definitely fine last year and now it is occasionally awful. Can the BBC really be that guilty? Anybody out there from the great institution care to enlighten us?

BTW I do sometimes get blips and squeaks which have to be removed by use of PVAStrumento. One of them nearly blew my speakers recently. Does that give us any clues?

The thing is that with a PC there is no headroom. 100% level will more than likely distort especially if you have bass/treble controls set. Another thing to consider in the case of Creative cards is that CMSS2 can sometimes get turned on (even when their utilities indicate it as being "off"). Have you tried foobar2000 with Kernel Streaming, as this will bypass most of the EQ and effects engines.


Some applications don't handle the raw MP2 streams very well, and I think that WinAmp is one such application. If you get clips and squeaks with live listening, e.g. in DVB-TV or in standalone mode on the DEC, then something is up with your reception (e.g. poor quality cabling) but in some cases there is nothing you can do to resolve it as the local interference from mopeds etc may be higher than the DTT field strength in your area.

What sound card are you using?

Start by setting the Master Volume to 75% and the Wave Volume to 50%. If you have noticed a change it may well be down to a sound card setting change.

I doubt that it's a sound card issue.

I'm hearing exactly the same thing here from the downloaded files, and my audiophile2496 has no problems.

btw, in technical terms, the BBC has been in decline for several years. There's nothing "great" about the parts of the institution that decide 80kbps mono is fine for stereo speech (BBC7 on DAB), or that ~2.5Mbps is fine for difficult to encode video (old programmes on BBC2 on DTT) etc etc etc.

They have repeatedly lied about the quality problems on DAB. The sorry story can be found by digging around this website:

http://www.digitalradiotech.co.uk/

Cheers,
David.

guysivey, have you tried the files in Audacity? It can handle DVB-T-sourced MP2 files correctly whereas WinAMP tends to produce clicks.

Hi,
I have tried most player apps as well as mp3/mp2 decoding dll's. Also mp2/mp3 editors like mp3directcut, and transcoding s/w.

Also playback via DVD player, iPod, Netgear mp101 wireless music player, in which cases the soundcard doesn't come into it.

Anything that can play these files plays them with the gravel effect, and plays the clicks if it hasn't been cleaned up with PVAStrumento.

Guy

Attached sample of Radio3's 'Performance on 3' on 28/04/2005 at 20:50

Taken from the bbc.co.uk site in real audio format at 132Kbps

I'd listen too, but it's past my bedtime.

I think someone from alt.radio.digital is recording it via DAB for us, so a full comparison should be possible.

Cheers,
David.

It is set to record on DAB here (Wavefinder + DABBar).
Let me know which chunk to extract (MP3DirectCut).

... later
it recorded here.
So - I now have a 130MB file ready to chop up and upload - just say which bit you want.

I recorded from about 11.45 to 12.35 on DAB, FM and DTT. If one of you wants to upload a sample from that part of the show then I can cut out the same sample from my files and upload them.

Listening to the files this morning, my personal opinion is to ditch recording via DTT (or DAB) and go back to FM...

No takers? Or uploaders?

If choice is the problem, I'd suggest 30 seconds of talking, and 30 seconds of music, with rough instructions as to where both parts are taken from in the broadcast so others can upload the corresponding parts.

Don't be shy - someone must go first!

btw, was the broadcast of generally high quality, so making this comparison worthwhile?

Cheers,
David.

Hi - been away for the w/e drinking beer, but ready now to do some comparisons. Dave was going to send me his files via yousendit.com, so I will PM the others to suggest the same, and then volunteer to do some comparing and post some samples of what I find. There should be some live music, talking, and CD tracks as well, from which I should be able to come up with something.
Cheers,
Guy

I've uploaded the following files:

http://83.142.53.30/~digital/R3_DAB_29_4_05_sample.mp2 (3.4 MB)
http://83.142.53.30/~digital/R3_DTT_29_4_05_sample.mp2 (3.5 MB)
http://83.142.53.30/~digital/R3_FM_29_4_05_sample.mp4 (5 MB)

Unfortunately, the FM sample is a lot louder than the others because I was recording them simultaneously with the DAB and DTT volume muted. The FM sample was encoded to AAC using Nero's Audiophile preset.

There's occasional brief "bubbling" sound on the DAB sample which is caused by reception. I think some software players accentuate these problems, but Winamp isn't too bad for them.

The samples were played at about 11.50.

Could you tell us what equipment you used and which transmitter you are on, digitalradiotech? When I have the rest of the samples I'll do a report on the result of all the comparisons with samples.
Cheers,
Guy

Denon TU260L Mk 1 FM/AM tuner fed by a half-wave dipole aerial, through a Pioneer A300X amplifier sampled using my Terratec EWX24/96 sound card, recorded using Cool Edit 2000, and encoed to AAC using Nero VBR Audiophile preset.

The BBC FM transmitter is Holme Moss.

If you're thinking about going back to FM then I would definitely recommend getting a Denon TU260L tuner, because you can pick them up on ebay for very little, and pretty much everybody agrees that it's the best entry-level FM tuner available. Also, the aerial you feed the tuner from is important, and it's well worth spending £10 - £25 on an aerial rather than just using the wire aerial that you blu-tak to the wall (mainly because you're limited to putting these wire aerials next to your hi-fi system where radio reception isn't usually very good due to signals bouncing off walls and stuff). The best place to put an aerial is outside on the roof, but failing that the next best is in the loft, failing that then put the aerial near a window. Mine's sitting on my windowsill.

Cheers for info, drt.

I have been recording from FM and doing a/d conversion for years, but thought that the advent of digital radio would allow me to capture something that had been encoded already, and encoded well. Seems like the jury's still out on that.
Guy