Sound quality on Freesat

[Dave2002]

My comments relate to Radio 4, last night - Tuesday 27th August. I thought the sound quality on Freesat was poor last night between 7pm and 8pm. I was listening on both DAB and Freesat, and the Freesat channel seemed to have very obvious digital compression distortion - as if a low bit rate encoder was being used. This was very obvious on speech. I didn't check R3 - but will do so over the coming days.

[Eine Alpensinfonie]

Freesat is generally better than DAB, so your observations are surprising, but worth investigating. The BBC is very keen on compression these days - on FM too.

I have some stereo open reel tapes of live broadcasts dating back to the 1970s. These confirm the new policy of deliberate restriction of dynamic range, so apparent on FM today, presumably a sneaky attempt to convince the general public that DAB is better.

[Dave2002]

Freesat is generally better than DAB, so your observations are surprising, but worth investigating. The BBC is very keen on compression these days - on FM too.

I don't normally find Freesat sound quality too bad, but it was last night. I have listened to enough digitally compressed material to have an idea what I'm listening to/for. You may know what I mean - I listen out for a sort of high frequency noise, which gives speakers a sort of lisp, and there are also some ringing sounds which get into the audio output sometimes. It's hard to explain, but years ago I found a web site about mp3 audio, and the originator had deliberately provided a lot of different digital compressed versions of the same material, and suggested listening to them so as to identify the artefacts at each level. It didn't take very long to spot the problems at the lower bit rates, and also to get a feel for the characteristics of some of the compression schemes. It is much harder if the bit rates are high, and the codecs are what are now considered to be good.

Perhaps someone turned the bit rate settings or the quality levels on the encoders down last night. Another possibility is that there was something in the signal - possibly from further back in the transmission chain - which interacted with the codecs.

Of course the compression on FM is dynamic compression, though they may also simply broadcast a decoded version of a digitally compressed stream, which could produce worse results than from an analogue source. I don't know enough about the interaction of FM modulation with decoded digital material, though there are issues in the digital domain with converting (transcoding) from one codec to another, such that the result will sound worse than if either codec is used by itself. Normally the degradation is not too bad, but it is theoretically there, and sometimes I believe it really is audible and unacceptable.

[IanR]

Hi
Does anyone know if the sound quality that is currently obtained from R3 via Iplayer (aac 320kb/s) is the same as from freesat channel 703???

[french frank]

Hi
Does anyone know if the sound quality that is currently obtained from R3 via Iplayer (aac 320kb/s) is the same as from freesat channel 703???

Hello, Ian :-)

I'm sure someone knows the answer - you might check back later if they aren't around at the moment.

[johnb]

Hi
Does anyone know if the sound quality that is currently obtained from R3 via Iplayer (aac 320kb/s) is the same as from freesat channel 703???

When I last looked the Radio 3 Satellite was mp2 192 kbps, the same as R3 on Freeview and DAB (when R3 DAB isn't reduced to 160 kbps). It is a markedly lower audio quality than iPlayer. (Not only is the bit rate lower but mp2 is a much less efficient codec).

Unless they have changed recently, the bit rates for Radio 1, 2, 3 and 4 on satellite are 192 kbps mp2.

[IanR]

Thanks for that but what a pity.
Its such a fag to get it through iplayer. My blue ray player has an iplayer embedded for tv and radio. My TV and the Humax sat box have iplayers for TV only. So you load up iplayer, tab up to Radio, select radio 3, then select a date, then select a programme and even then its not necessarily live ... whereas through the sat box select channel 703 Done . The signal that comes via the internet that feeds the iplayer must be getatable another way surely ???

[Frances_iom]

Thanks for that but what a pity.
.... The signal that comes via the internet that feeds the iplayer must be getatable another way surely ???

It is but the BBC tends to issue cease + desist commands to prevent such easy access - when I asked about one small bedside internet radio was told that couldn't handle iPlayer tho that of course is why I wanted it - I suspect it is a mechanism to restrict access to just the 1 week by preventing easy recording

[johnb]

I use a Squeezebox Touch, networked to a server, to feed the iPlayer (and my record collection) to my audio system. I can also play Spotify and Qobuz through it.

Sadly Logitech discontinued the Squeezebox product line some time ago.

[jayne lee wilson]

Thanks for that but what a pity.
Its such a fag to get it through iplayer. My blue ray player has an iplayer embedded for tv and radio. My TV and the Humax sat box have iplayers for TV only. So you load up iplayer, tab up to Radio, select radio 3, then select a date, then select a programme and even then its not necessarily live ... whereas through the sat box select channel 703 Done . The signal that comes via the internet that feeds the iplayer must be getatable another way surely ???

Always best via computer...(fed into a DAC)...
For the live feed, easiest via iTunes: click on RADIO - double click on CLASSICAL - double click on BBC RADIO 3 HIGH. It should play immediately at 320kbps AAC-LC, far better quality than any of the mp2 variants at whatever bitrate, and better than FM with a much wider dynamic range. This is 100% stable here, via BT Infinity, especially if you hardwire via ethernet - but a good wireless connection should be fine (avoid Home Hub 4!).

For Listen again, access via R3 Homepage or iPlayer Radio 3. Bitrates tend to vary a little more, 128/192/320 kbps AAC, but are usually 320. Subjectively I always prefer the live feed, and bear in mind that R3 is the only station broadcasting at this rate now, even Berlin DCH is back at 256 AAC (to help accommodate auto-switching of Video quality). Fond memories of when they ran at 320, up to the autumn of 2010 - what a treat those live concerts were!.

[David-G]

For Listen again, access via R3 Homepage or iPlayer Radio 3. Bitrates tend to vary a little more, 128/192/320 kbps AAC, but are usually 320.

I was under the impression that R3 on iplayer is always 320 kbps. Am I wrong? I could have sworn that this question has been asked before, and answered in the affirmative.

[johnb]

Perhaps it is just luck but the R3 on iPlayer has always been 320 kbps AAC-LC (for both live and listen again) when ever I have listened to it.

The only time it was not at 320 kbps was a few years ago when there was a bug and some of the iPlayer Listen Again programmes were going out at circa 56 kbps for a few weeks. (I ended up doing a daily survey of bit rates for each programme and funnelling the results to the techie team.)

By the way, you should ignore the bit rate of 128 kbps that is quoted on the iPlayer Radio 3 window. It is wrong. It has been wrong for years.

[Bryn]

The files on the iPlayer on demand option have all too often been offered only in mono and at around 48kbps HE-AAC in the past few months. Sometimes they get sorted after the "Contact Us" system is used to alert the iPlayer Team to the problem, but sometimes they never do get put right within the claimed 7 days of availability. Until about two and a half years ago the best on offer was 192kbps mp3.

[Dave2002]

When I last looked the Radio 3 Satellite was mp2 192 kbps, the same as R3 on Freeview and DAB (when R3 DAB isn't reduced to 160 kbps). It is a markedly lower audio quality than iPlayer. (Not only is the bit rate lower but mp2 is a much less efficient codec).

Unless they have changed recently, the bit rates for Radio 1, 2, 3 and 4 on satellite are 192 kbps mp2.

I'm not sure what the Freesat rates are, but I suspect they are normally higher than 192 kbps.

I have many recordings of CD Review - which normally lasts 3 hours - 3600*3 = 10800 seconds.

Many of the files (.ts files with the data) are about 312 Mbytes = 8*1000*312 kilo bits = 249600 kbits.

Dividing and ignoring any small packaging overheads gives a data rate of about 230 kbps, which notionally could be 256 kbps VBR, or something between 192kbps and 256 kbps.

The equivalent file from the Britten day on 23rd November was smaller, about 194 Mbps. However, checking showed it was only a 2 hour programme, so the bit rate calculation comes to about 213 kbps.

For comparison, Front Row on R4 is typically 30 minutes = 1800 seconds. One Front Row file is about 45 Mbytes, so the calculation based on that gives almost exactly 192 kbps. That file was from January earlier this year.

I don't have any software which I know of which can check the encoding rates by examining the data in the files.
Maybe VLC is able to detect the rates in the file.
Also, I thought that Freesat might be using aac rather than mp2 - but I'm not sure.

[johnb]

Dave,

To estimate the bit rate from the file size you need to extract the mp2 from the Transport Stream file (or save the data as Program Stream instead of Transport Stream). Relying on the ts file size will give misleading results as ts files can contain other data as well as the mp2 (in the case of TV programmes the saved ts file can be very much larger than the mpg it contains).

James Cridland in Aug 2012 wrote of radio via both satellite and freeview: "Sound quality: Digital, between 96 and 192k, MP2 encoded." (Though he seems to ignore the R3 bit rate in his iPlayer summary.)

http://www.mediauk.com/article/32730/what-radio-platform-is-best

Perhaps things have changed since then, but I doubt it.

(Sorry to be ultra picky but in the case of your CD Review example - the programme is actually 3 hr 15 mins, though of course you might only have recorded 3 hours, and to convert mega bytes/bits to kilo bytes/bits you need to multiply by 1024, not 1000. But I am sure you already knew all that.)