Ticking/Crackling on iPlayer

[Guest]

I occasionally listen to R3 at work and have noticed a horrible content related crackling appearing recently. At the moment, I just want confirmation that it's not just me or my equipment, so any confirmation of the following example would be handy to know:

The program was this http://www.bbc.co.uk/iplayer/episode..._Shostakovich/ (Live in Concert from last Friday 27th September).

Scroll to about 42:30 - very quiet start, then clarinet begins at about 42:47, accompanied by a regular ticking/crackling. The crackling gets worse as the clarinet increases in volume, disguised in part as the orchestra accompanies. This continue all the way through and is very bad in the final notes at 58:22. A similar effect in the next piece eg at 1:02:11, I think it continues all the way through the program. It is most noticeable when you have a loud solo instrument, though sometimes it's not there (1:05:55 vs 1:06:10)

This program is only available until 10pm tonight, so if you are not reading this today (Friday 4th Oct) this will be irrelevant. If I find a more recent example, I'll edit the post.

(later) can also hear evidence btween 13:49 and 14:20 in http://www.bbc.co.uk/iplayer/episode...vich_(part_2)/

I've listened via streaming on a PC with Windows 7, a Nook HD+ Android tablet, on a Chromebook running ChrUbuntu and a Chrome browser and downloaded the stream using get_iplayer and played back with VLC. All the same.

It sounds to me like some particular combinations of frequency/amplitude components in the source induce an encoder problem.

[french frank]

Hello, garyc - and welcome. Hope someone will step in with a reply soon.

[robk]

I have just had a listen using Internet Explorer and the clicking is clearly audible. I am not qualified to suggest what is causing it, but some of the Techies might have thoughts about it.

[garyc]

thank you. At least I know I'm not going mad!

[edashtav]

I occasionally listen to R3 at work and have noticed a horrible content related crackling appearing recently. At the moment, I just want confirmation that it's not just me or my equipment, so any confirmation of the following example would be handy to know:

The program was this http://www.bbc.co.uk/iplayer/episode..._Shostakovich/ (Live in Concert from last Friday 27th September).

Scroll to about 42:30 - very quiet start, then clarinet begins at about 42:47, accompanied by a regular ticking/crackling. The crackling gets worse as the clarinet increases in volume, disguised in part as the orchestra accompanies. This continue all the way through and is very bad in the final notes at 58:22. A similar effect in the next piece eg at 1:02:11, I think it continues all the way through the program. It is most noticeable when you have a loud solo instrument, though sometimes it's not there (1:05:55 vs 1:06:10)



(later) can also hear evidence btween 13:49 and 14:20 in http://www.bbc.co.uk/iplayer/episode...vich_(part_2)/

I've listened via streaming on a PC with Windows 7, a Nook HD+ Android tablet, on a Chromebook running ChrUbuntu and a Chrome browser and downloaded the stream using get_iplayer and played back with VLC. All the same.

It sounds to me like some particular combinations of frequency/amplitude components in the source induce an encoder problem.

My equipment shows the same issues, Gary, although neither example was so obtrusive as to destroy my enjoyment of the music and WOW - didn't Michael Collins "float" his entry in the Copland Concerto supremely well? I was entranced by him ( if not by the City of London Sinfonia that sounded scrawny and, sometimes, ill-disciplined). So, thanks very much for pointing me to the performance although I'm sorry to confirm your annoying clicking.

[garyc]

My equipment shows the same issues, Gary, although neither example was so obtrusive as to destroy my enjoyment of the music and WOW - didn't Michael Collins "float" his entry in the Copland Concerto supremely well? I was entranced by him ( if not by the City of London Sinfonia that sounded scrawny and, sometimes, ill-disciplined). So, thanks very much for pointing me to the performance although I'm sorry to confirm your annoying clicking.

Don't want to sound like a moaning minnie but it seems to be endemic - listening now to Rachmaninov Piano Concerto No 3 http://www.bbc.co.uk/iplayer/episode...inov_(part_2)/ and the crackling/ticking is there from the beginning. I'm listening on closed headphones so maybe it's more apparent to me and in some ways more irritating than just background hiss on FM. It is really very unfortunate that what should be a flagship top quality signal is marred by this obvious degradation. Clearly there is no monitoring of the iPlayer signal else this would surely have been picked up and corrected.

A couple of years ago there existed a BBC blog where stuff like this could be reported, but that was closed down and it seems they don't care anymore. What is especially annoying is that I have come back to listening to radio now that it is available in almost pristine quality (320kbps should be indistinguishable from CD) for very little outlay in terms of home equipment and for a ha'porth of tar and/or lack of technical expertise at the BBC is spoiling the whole deal.

[Sir Velo]

CDReview is only available on the low bandwidth option. It could well be that what you are experiencing is due to the low quality of the recording. The Head of Digital, Radio 3, has admitted to me that they are having technical issues at present with iplayer.

[Bryn]

I hear the crackling referred to but wonder, did anyone here just happen to save the DAB or FM version of this broadcast? The reason I ask is that it might help establish whether this was a coding artifact or possibly something earlier in the transmission chain between instrument and radio listener.

[I should add that I did briefly consider the possibility that the sound originated within the clarinet, but swiftly dismissed it.]

[garyc]

CDReview is only available on the low bandwidth option. It could well be that what you are experiencing is due to the low quality of the recording. The Head of Digital, Radio 3, has admitted to me that they are having technical issues at present with iplayer.

The only programs I've noticed the problem on (so far) have been the Live in Concert BBC recordings. A direct download of the live recording of last Friday's London Sinfonia concert from iPlayer (that I made with no re-encoding) was 320kbps AAC and had the problem. To me it sounds like an encoder problem induced by particular content features. The Mark Elder Shostakovitch 7 from the other night suffers from it too. Once you are aware if it, it becomes very obvious.

I'm listening live to tonight's Shostakovitch 8 with the BBC NOW on my Chromebook and I can't hear anything untoward so far but I'll check the iPlayer recording tomorrow.

(edit Sat): the iPlayer recording was clean, though I did notice it was a full 171 minute recording with before and after - maybe its the editing process of cleaning up the start/end and splitting into part1/2 that's introducing the problem?

The recoding now seems to be available in edited form http://www.bbc.co.uk/iplayer/episode..._Shostakovich/ and the ticking/crackling is defintely there eg solo voice @ 13:06, definitely gets worse as the voice gets louder. I can't be 100% sure but I have a strong suspicion this nastiness is being introduced when the raw recordings are trimmed.

[OldTechie]

I occasionally listen to R3 at work and have noticed a horrible content related crackling appearing recently. At the moment, I just want confirmation that it's not just me or my equipment, so any confirmation of the following example would be handy to know:

<snip>

I've listened via streaming on a PC with Windows 7, a Nook HD+ Android tablet, on a Chromebook running ChrUbuntu and a Chrome browser and downloaded the stream using get_iplayer and played back with VLC. All the same.

It sounds to me like some particular combinations of frequency/amplitude components in the source induce an encoder problem.

I have tried it in Windows 8 and on an iPad. The clicks are there on both. (The iPad does not have Flash so the streaming must be different - but the clicks are the same.)

The clicks seem to be there on the low bitrate version as well.

I have not noticed such continuing clicks on any live feeds, though I do sometimes hear the odd one or two in the course of a concert. Has anyone heard them on anything other than Listen Again?

[garyc]

I have tried it in Windows 8 and on an iPad. The clicks are there on both. (The iPad does not have Flash so the streaming must be different - but the clicks are the same.)

The clicks seem to be there on the low bitrate version as well.

I have not noticed such continuing clicks on any live feeds, though I do sometimes hear the odd one or two in the course of a concert. Has anyone heard them on anything other than Listen Again?

The same AAC 320k encoded stream will just be wrapped up differently for transport on Win 8 and iPad, so it would be expected that the same artifacts appear on both.

[OldTechie]

The same AAC 320k encoded stream will just be wrapped up differently for transport on Win 8 and iPad, so it would be expected that the same artifacts appear on both.

Yes, if the problem is not in the transport system. It just indicates that it really is the source AAC data that is faulty, not that it has intermittent delivery due to some CDN problem. I thought that the iPlayer LA version would be sub-clipped from the live AAC 320 K stream - but if the fault is only on the LA feeds then maybe they are encoded separately.

[Bryn]

In my experience, the initial LA postings, replete with the close of the preceding programme and start of the following one, is later topped and tailed by the iPlayer team.

I stopped bothering to record the FM broadcasts and DAB mp2s when the LA version of the HD Sound option became pretty reliable. I might have another go on Monday and Tuesday evenings to compare and contrast with the HD Sound 'live' and LA versions. Chances are that no crackling will occur those nights, (sod's law and all that).

[gedsmk]

In my experience, the initial LA postings, replete with the close of the preceding programme and start of the following one, is later topped and tailed by the iPlayer team.

I stopped bothering to record the FM broadcasts and DAB mp2s when the LA version of the HD Sound option became pretty reliable. I might have another go on Monday and Tuesday evenings to compare and contrast with the HD Sound 'live' and LA versions. Chances are that no crackling will occur those nights, (sod's law and all that).

What a relief! regarding the Hallé performance of Shostakovich 7 the other night, first I thought it was my computer's fault (top of the line sound card) and then perhaps my own ears! The original broadcast over iplayer sounded fantastic, and I was distressed by the recorded version on later listenings - the crackling you mention is quite clear, esp when the whole orchestra is involved. There are slips here and there in the performance but the overall impact is so "gut busting" that it is certainly worth consideration for a CD.

[Bryn]

Oops, I forgot to record last night's broadcast, and tonight's is a substituted repeat from last year's EIF. I will try and remember to try multiple sources tomorrow or later in the week (very much a matter of how early I get home from work).