Dynamic Range Compression/Fader Fiddling on iPlayer/Sounds

[Bryn]

Yes, AAC is just the tech term for the codec used - with the program running, you can right-click on the Sounds window (below the slider line) to check what you're getting. You should see something like "320 kbps dash" etc.
All the BBC Radio channels should be at 320 kbps aac, IIRC this can be reduced sometimes for various reasons, though I've never found R3 any lower. The Dvorak should be a good test piece as it does have a pretty wide dynamic range, some big tuttis and climaxes with soft cadenzas and solos, and a slow movement that is mainly soft with a big outburst later on.

The only problem is, its so lovably involving it can be hard to switch about if one gets into it...

You don't really need huge Bruckner climaxes to study this though. Recalling the experience of FM, one would become wearily familiar with the first allegro of a Haydn Symphony going fairly well (if less punchy than ideal), then the slow movement would get that merciless fading up....you just have to know what to listen for. With quiet endings (Mahler 9!), the fading-up would rise with the hall atmosphere, then pull back crudely as the applause began....just a dead giveaway, baby...

AAC = Advanced Audio Codec. It is Apple's codec of choice for lossy compression, though they wrap it up in an m4a 'jacket'. It comes in two main flavours, AAC-LC (the LC standing for Low Complexity) and HE-AAC (i.e. High Efficiency - used mainly for lower data rates such a 128kbps). Sounds uses AAC-LC at 320kbps for superior fidelity to the original. Those who use get_iplayer will be familiar with the m4a wrapping. That wrapping is done by the get_iplayer program. The BBC sends out 'raw' AAC-LC.

E&OE.

Re references to dynamic limiting in some Prom audio engineering, the start of 2011 was particularly bad. This was when Roger Wright, of whoever bore direct responsibility, farmed the audio engineering out to a company previously versed in outside sports broadcasting, with predictable dire results.

[Ein Heldenleben]

My initial thought is that on first entry the cello is far too far forward in the balance and too loud ! That’s spot mikes ( and cellists ) for you . Ah now the fader has been slightly eased off.
Nice playing - I’d give anything to be able to play some of the melodies in this total masterpiece ....

[Bryn]

My initial thought is that on first entry the cello is far too far forward in the balance and too loud ! That’s spot mikes ( and cellists ) for you . Ah now the fader has been slightly eased off.
Nice playing - I’d give anything to be able to play some of the melodies in this total masterpiece ....

Is that the FM, the DAB or the HD Sound version you are dealing with?

[Ein Heldenleben]

Is that the FM, the DAB or the HD Sound version you are dealing with?

FM : but that particular effect of an over loud solo first entry should be the same on all output and is very common . . The balancer would have been caught off guard perhaps because the cellist either came in louder than in rehearsal , or some one unhelpfully moved the mic nearer, or the fader on the cello mic was set higher than it should have been (unlikely) .
I thought it was a really good balance with very good stereo definition and instrument placement .Perhaps slightly over prominent cello but all a matter of taste . Yes there was evident compression but completely acceptable for me and no limiters crashing in on the tutti. There was even a pretty good pp section at the end so an acceptable dynamic range for me. But I missed most of the slow movt as I was cooking.
I also really enjoyed the performance ...

[jayne lee wilson]

Well that was OK wasn’t it? More than OK…!

So on Sounds at 320 kbps via Firefox (latest), usual dedicated Macbook etc filtered/regenned USB to the Dac....

Warm spacious natural balance, with good depth and fine dynamic range - plenty of subtlety within the dynamics too. Fine inner detail (Tali seems to have an exquisite ear) and a nice ambience around instruments at lower levels.
No sign of boost or fade anywhere. Cello(**) naturally placed in relation to the orchestra (perhaps very slightly emphasised in the mix at higher levels, but with very soft pps, so perhaps the mic perspective was simply closer than mid hall...never unnatural at all).
Good to hear the conductor drawing (and the production revealing) extra power from the orchestra in the climaxes toward the end - which was a thrilling conclusion to an excellent performance.
((**) First solo entry wasn't at all "overloud" on the aac feed, which displayed the natural dynamic stability and consistency I've come to expect.)

Hearing the end of the 1st movement, and passages toward the end of the 2nd on FM (helpfully some seconds ahead of the Sounds feed) revealed the usual boosted pps and limited climaxes. All too obviously I'm afraid, especially on solos.
I've noticed this dynamic difference in quieter passages consistently with direct aac/FM comparisons, with FM often much louder. It seems to be auto-set via Optimod or whatever limiter they use now.
So the usually observed comparative values - no surprises tonight…

Returning to the opening to hear the tutti/first solo entry, I felt compelled to play through the whole first movement again - really wonderful technically and musically.

[Ein Heldenleben]

Completely agree (on FM here ) Jayne on the performance and excellent balance . If anything the Sibelius sounds even better. This conductor is new to me and I think this is a terrific performance. The BBC NOW are playing quite beautifully...

[jayne lee wilson]

Definitely back for the Rouvali Prokofiev 5th tomorrow (21/02 Part 2 around 2045 - just about OK for Any Questions addicts...)...

There might really be something in this live Radio 3 Concert thing....!

You don't know what you got till its gone.... etc....

[cmr_for3]

Is the upshot of this thread that one gets better sound quality via Sounds when listening live as opposed to on demand? Or have I got this wrong?....

[Bryn]

Is the upshot of this thread that one gets better sound quality via Sounds when listening live as opposed to on demand? Or have I got this wrong?....

The audio quality should be identical. They do, however, very occasioally do some minor editing prior to uploading the HD Sound on demand files. Also, if you are just that little too quick in accesing the on demand file, it might well only be at 128kbps. If so,try again a few minutes later. The initial upload is done automatically and often starts and ends early. Such errors usually get corrected within a day or two. Having had drop-out when listening to the HD Sound stream live, I tend to do all my HD Sound listenng on demand.

[johnb]

No complaints from me about the Dvorak Cello Concerto (I missed the Sibelius).

It will be interesting to listen to Bruckner 8 next Thursday - which should be more challenging.

[jayne lee wilson]

Prokofiev 5th RFH 9/02/20 Sounds aac webcast 21/02/20, Philharmonia/Rouvali - again excellent, no audible dynamic manipulation or constraint, very good balance and dynamic range in a production faithfully presenting a fascinating, in many ways remarkable performance from the Philharmonia and their Principal Conductor designate....

Very powerful climaxes in 1st, 3rd and last movements.....true, soft pps.... (it really doesn't have to be Bruckner, you know....)

[Bryn]

Prokofiev 5th RFH 9/02/20 Sounds aac webcast 21/02/20, Philharmonia/Rouvali - again excellent, no audible dynamic manipulation or constraint, very good balance and dynamic range in a production faithfully presenting a fascinating, in many ways remarkable performance from the Philharmonia and their Principal Conductor designate....

Very powerful climaxes in 1st, 3rd and last movements.....true, soft pps.... (it really doesn't have to be Bruckner, you know....)

Yes. As I understand it, the original digital processing tends to be at high resolution. They aim for a maximum peak of -6dB, which gives them a fair bit of leeway in terms of clipping. As long as they use a sound check of the loudest passages, for the eventual HD Sound stream no further overall level adjustment should be needed. Of course, things will not always run to plan and subtle level mixing changes might be called for 'on the night'.In a venue the engineers are used to, basic levels will come as secnd nature.

[Ein Heldenleben]

Prokofiev 5th RFH 9/02/20 Sounds aac webcast 21/02/20, Philharmonia/Rouvali - again excellent, no audible dynamic manipulation or constraint, very good balance and dynamic range in a production faithfully presenting a fascinating, in many ways remarkable performance from the Philharmonia and their Principal Conductor designate....

Very powerful climaxes in 1st, 3rd and last movements.....true, soft pps.... (it really doesn't have to be Bruckner, you know....)

No Indeed I stupidly sat in the second row at the RFH for a (terrific) performance of this by Jurowski and the LPO a few years back and my ears were ringing the next day. It must be one of the most consistently loud symphonies in the repertoire - almost as if Prokofiev was employing the orchestral equivalent of compression...

[Ein Heldenleben]

Yes. As I understand it, the original digital processing tends to be at high resolution. They aim for a maximum peak of -6dB, which gives them a fair bit of leeway in terms of clipping. As long as they use a sound check of the loudest passages, for the eventual HD Sound stream no further overall level adjustment should be needed. Of course, things will not always run to plan and subtle level mixing changes might be called for 'on the night'.In a venue the engineers are used to, basic levels will come as secnd nature.

Unless we are talking about different things I thought the maximum permitted level employed by Uk broadcasters was +8dBu - which is 6 on a PPM ....

[cmr_for3]

The audio quality should be identical. They do, however, very occasioally do some minor editing prior to uploading the HD Sound on demand files. Also, if you are just that little too quick in accesing the on demand file, it might well only be at 128kbps. If so,try again a few minutes later. The initial upload is done automatically and often starts and ends early. Such errors usually get corrected within a day or two. Having had drop-out when listening to the HD Sound stream live, I tend to do all my HD Sound listenng on demand.

Thanks Bryn for the explanation and clarification