Prom 1 - HD Sound Severely Limited/Clipped

[johnb]

SA,

I'll re-do my original graph to show the announcements and music.

[Edit] Done!

[Serial_Apologist]

SA,

I'll re-do my original graph to show the announcements and music.

[Edit] Done!

Thanks johnb

[johnb]

PS Please let me know if the size of the pics means that the right hand side is cropped off on your display and I will re-do them.

[PJPJ]

Johnb, that was my first attempt at recording the HD - hence the incorrect 48 instead of 44.1. Simply recorded using Goldwave. I did amplify as the sound was very low level.

I used to grab the Listen Again using ipdl until it ceased to work (native 192/mp3) and now use Radio Downloader (not native). How do you get the original aac from the HD/320 stream?

I've sent you a PM.....

[johnb]

It looks as though the Radio 3 HD sound was back to normal for Prom 2. Thank Heavens!

Either the sound engineers have sorted out their problems or ... just perhaps ... it might have been something to do with the TV also being broadcast for the concert. (On the TV sound the music was also limited, this time to ~-10dB whereas the announcer and interval feature sound wasn't, though it only peaked to ~5dB.)

[johnb]

PJPJ,

If you are capturing the iPlayer or HD sound - the iPlayer volume control attenuates the volume so set it to maximum for the best result.

I'm PM tomorrow about the other matters.

[Bryn]

It looks as though the Radio 3 HD sound was back to normal for Prom 2. Thank Heavens!

Either the sound engineers have sorted out their problems or ... just perhaps ... it might have been something to do with the TV also being broadcast for the concert. (On the TV sound the music was also limited, this time to ~-10dB whereas the announcer and interval feature sound wasn't, though it only peaked to ~5dB.)

Fingers very firmly crossed for The Gothic then. It does seem distinctly possible that during the performances themselves, the television limiting level was also applied to the Radio 3 stream for the First Night. Off to bed now. I have to be up early to get the first coach to the RAH.

[PJPJ]

Not recorded by me this time - here's the Brian from HD/320



Uploaded with ImageShack.us

[Fingers]

I am afraid that the sound on the Prom 4 (Brian - Symphony No.1, The Gothic) was severely clipped. For me it was 9.2dB below peaks that could be transmitted. I have tried to attach a screen capture of the waveform of the whole concert with applause at the start and at the very end of the music. But I keep getting an error message with Google Chrome browser.

The broadcast was captured using a PC based Nebula TV tuner on Freeview from the Rowridge transmitter, IOW.

The limiting applies just to the music, whereas the applause and announcements at the end show they were NOT compressed/limited and were several dB higher than the music. What is the BBC up to? Is this deliberately being slugged?

[johnb]

Well this is the original, native HD Sound aac stream for Prom No 4:



The Freeview mp2 is very similar.

[johnb]

With the Gothic Symphony some dynamic level management would have been absolutely essential. My guess is that they employed something similar to the dreaded Optimod that is used on FM but that the processing happened on site (hence the announcer not being subject to the limiting). However, setting the limiting level to ~-10dB seems inexplicable.

So far the only two concerts affected this way (ever, to my memory) have been Proms 1 and 4. It is just possible that Prom 1 was used as a testing ground for the methods they were going to use to cope with the dynamics of the Gothic and that is the last we will see of this limiting.

(It is also possible that the outside broadcast crew contracted by the BBC for this seasons Proms has little or no experience with the RAH and/or classical music in general.)

[Fingers]

Hi johnb,

I have checked and the waveform I wanted to upload is obviously identical. It means that the limiters are way before the final leg of transmission (FM, Freeview, Internet) where there might be differences between the various platforms.

How can the BBC be made aware of this appalling engineering? Does anyone from BBC read this forum? I was looking forward to the Gothic and it has been reduced in dynamic range to a pop track!

[Frances_iom]

Hi johnb,
..I was looking forward to the Gothic and it has been reduced in dynamic range to a pop track!

you must be fortunate in the pop that assaults you - that I have at time to endure has I doubt less than 6db dynamic range - totally companded to destroy any musicallity - however just as R3 is moving to widen access' by concentrating on playlists, commercial charts and judging from Joan Baez this morning the music of the yoof of 45yrs ago then I guess we will have to get used to the loss of the once world famous BBC engineering

[Fingers]

The sad thing is that I have to admit to being a BBC engineer once - and a sound engineer too! But that was in the early 1970s, three careers ago.

I agree that the BBC's beacon of excellent engineering has long since faded. I still cannot believe the poor quality of DAB classical stations. Why BBC jumped with an old and poor standard I will never know. And now my beloved Proms are similarly affected by poor dynamic range. Oh dear! The BBC has really lost its way.

[Frances_iom]

The sad thing is that I have to admit to being a BBC engineer once - and a sound engineer too! But that was in the early 1970s, three careers ago.

I agree that the BBC's beacon of excellent engineering has long since faded. I still cannot believe the poor quality of DAB classical stations. Why BBC jumped with an old and poor standard I will never know.

I too once (many decades ago) worked briefly as an engineer at BBC - the DAB choice was I think originally made with impression that they would give 256kb/s to each of the 4 national stations - at which it sounded excellent in all the early technical demos I heard (better than FM ) - then politics and over arching ambition by the totally technically ignorant programme controllers got in the way and we landed up with the barely acceptable mess of today - however once FM is gone then the standards can again be dropped as by then most listeners will complain if companding is not applied (and that awkward R3 will probably have gone by then)