From: Jim web
Sent: Sunday, August 6, 2017 12:18


In article
<caafm_yzbie08tvvnbzp+k+r81dvifbtaqauj_lvccskxtx1...@mail.gmail.com>, Paul
Thornett <pthorn...@gmail.com> wrote:

Well, that's funny. I've been playing Proms on the iPlayer site (nothing
to do with GIP) and recording the stream with Audacity since the Proms
>started (as I live in Oz, playing and recording a live stream is
>impractical given the time difference).

>MediaInfo shows a constant bit rate of 1411 kb/s, a sampling rate of
>44.1 kHz and a bit depth of 16.

Since the BBC will be using 48k for the standard streams (ignoring
'podcasts') that alerts you to "MediaInfo" reporting something which has
been converted after reception.

1411 kb/s is the LPCM rate for stereo 44.1k/16bit.

If you then do the same for a live Prom, you get exactly the same
results from MediaInfo,

if you do, something in your system *prior* to "MediaInfo" is farting about
with the audio and changing the sample rate.

If Paul Thornett right clicks on the Radio iPlayer, or whatever it is called now, it will tell him the bit rate. It will be 320kbit/s unless he has a slow connection or is suffering from geo-blocking.

He is not making a digital recording. The digital to analogue converter in his sound card is feeding an analogue signal to his speakers and Audacity is taking that analogue signal and converting it to digital. As you point out, the stream from the BBC has a sample rate of 48kHz. Audacity’s default sample rate is 44.1kHz, which is where that sample rate comes from. The additional quantisation noise from re-sampling is small. Far greater distortion is introduced by the digital to analogue and then analogue to digital conversions.

Better quality will be achieved by using get_iplayer to download the streams, even at 128kbit/s. get_iplayer offers AAC at a range of bit rates up to 320kbit/s. get_iplayer will not deliver the FLAC streams. If he wants FLAC from the PROMs he will have to get up in the early hours of the morning, but as you have pointed out all R3 output is available live (or delayed 2 minutes or so) as FLAC during the trial.



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