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Re: iPlayer radio bitrates

Messages in this topic: 2 View All
James R CurryMar 19, 2017

Hey,

I'd seen 384kbps on your original post and hadn't noticed the line about the full bitrate .wav file when I'd clicked the link. So apologies there and thanks for pointing it out.

I've examined the scripts and played with the Greasemonkey extension. Here are my findings:

1) Option 2 (All with batch files) fails. I get an empty notepad document on the first step. I'm not sure whether this is because the BBC have changed something, or my version of Windows/IE is too new. Either way, this is a non-starter.

2) Option 1 (Greasemonkey) gets me the command line. However, I get a 403 (forbidden) trying to download. Yes, I'm using a UK IP address, and not one the BBC have blocked. In fact, I'm using get_iplayer in another window as I write this.

From what I can tell, these scripts don't do a lot that get_iplayer doesn't. They're using ffmpeg to process the m3u8 playlist file and save the output. That m3u8 file doesn't contain anything that looks remotely like an uncompressed WAV stream, and the system seems to rely on changing the file extension of the last parameter to get different output. Here's the thing -- that last parameter is ffmpeg's output format, and ffmpeg will automatically transcode to match the extension you provide. So as best as I can tell (and by my own admission, actually fetching the m3u8 file is broken), to get that .wav file you're actually transcoding the best quality available to an uncompressed wave. No real benefit, there.

As for mp2 files -- I believe that the BBC has used mp2 because that's what's used by DAB radio? With a high quality encoder, at the same bitrate, I'm given to believe that mp3 is superior, but I did a little research while writing this response. The answers I'm finding are murky, with people claiming that an mp2 file is "Half the size of a PCM wav" while an mp3 file is "One tenth". Of course, that makes absolutely no sense if both files are encoded at the same bitrate, as the size will be the same.

However, murky answers about mp2 vs. mp3 not withstanding, I maintain my claim about aac. It's a newer codec, and offers significant improvements over both mp2 and mp3 at the same bitrates.

Once more, if I'm wrong or am missing anything here, do let me know.

On Sun, Mar 12, 2017 at 4:12 PM, Clitheroe Kid clitheroekid@... [just-a-minute] <just-a-minute@...> wrote:
I'm not a computer expert. But I think you may have missed the point.

The website in question is offering access to the BBC's real, actual stream. It's offering you the .WAV stream that underlies all of the BBC's streaming content.

Go back to the site, read again what it explains there, then download an iplayer file, giving it the extension .WAV (instead of the default .FLV extension allocated to streams by the BBC), and you'll find the actual 1500 kbps uncompressed stream downloading. Only .mp2 will stream at 384 kbps, although .ts will stream at 320 kbps. The .mp3 or .m4a streams run at only 128 kbps.

MP2 was designed for high bitrates, so it in fact performs better than other options at 384 kbps, whereas it performs relatively poorly at 80 kbps (the BBC use mp2 as a DAB stream at 80 kbps).

Website : http://myweb.tiscali.co.uk/ bridip/clitheroe/iplayer.htm

______________________________ __________

From: just-a-minute@... [just-a-minute@... ]
Sent: 03 March 2017 14:14
To: just-a-minute@...
Subject: Re: [just-a-minute] iPlayer radio bitrates

Interesting --

The brand new Dash AAC streams and the existing HLS AAC streams are both 320kbps. I'd certainly take a 320kbps AAC file over a 384kbps MP2 file, as the quality should be better due to improvements in the more modern codec. In fact, MP3 dropped supported for 384kbps for much the same reason -- a 320kbps MP3 will sound superior to a 384kbps MP2 in most cases.

Do you happen to know the underlying codec used in the MPEG or TS files? I suspect that it's the same 384kbps MP2 data, but I haven't grabbed the files to double check.

On Thu, Mar 2, 2017 at 3:14 PM, Clitheroe Kid clitheroekid@...< mailto:clitheroekid@hotmail. com> [just-a-minute] <just-a-minute@... <mailto:just-a-minute@ ...>> wrote:
Get_iPlayer is sometimes useful, but for the full bitrate stream - the 384 kbps stream - you need other solutions.

Here is a very straightforward way to get that stream with radio downloads from BBC iPlayer -
http://myweb.tiscali.co.uk/ bridip/clitheroe/iplayer.htm

______________________________ __________
From: just-a-minute@...< mailto:just-a-minute@ ...> <just-a-minute@... <mailto:just-a-minute@ ...>> on behalf of James R Curry scratchy@...<mailto:scratc hy@...> [just-a-minute] <just-a-minute@... <mailto:just-a-minute@ ...>>
Sent: 08 December 2016 15:10
To: just-a-minute@...< mailto:just-a-minute@ ...>
Subject: [just-a-minute] iPlayer radio bitrates

I'm reviving a dead topic!

Remember when I said that the iPlayer serves a better radio bitrate to listeners in the UK, and you all laughed?

Well, okay, very politely corrected me.

It turns out I was right!

Although I'm not so much telling you this to gloat, and more as helpful information for those who download shows from the iPlayer. Anyway, there's a guide to formats for get_iplayer here. I think part of the confusion may have been that you need a recent build of get_iplayer to grab the 320kbps stream:

https://github.com/get- iplayer/get_iplayer/wiki/ modesref

--
James R Curry
scratchy@...<mailto:scratc hy@...><mailto:scratchy@ 3pb.net<mailto:scratchy@3pb. net>>

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James R Curry
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