TV Audio Bitrates

RS richard22j at
Fri Aug 25 16:04:32 PDT 2017

On 25/08/2017 16:28, Vangelis forthnet wrote:
 > ...
 >But still the "Not so" part of his post stands true for various pids 
 >outside the main BBC TV channels...
> Just try (with 3.02)
> get_iplayer --type=tv --pid=p059b38x --tvmode=hvfsd
> (pid expires in 2 days) and you'll discover it fetches as a 128kbps hvf* 
> mode... One other oddity for this pid is it's not available as legacy 
> hls* (/flash*) tvmodes, only dvf*/hvf*.
> I guess a better choice of wording would be:
> "GiP 3.02 tries to download every hvf* tvmode with a 320kbps audio 
> stream, whenever that one is available on the CDN server"
> Notice I didn't say "when it's available by the BBC", because the BBC do 
> not officialy and publicly make such a stream available via their 
> iPlayer interface.
> It was a code hack first implemented by youtube-dl devs (Python) and 
> then ported to GiP (perl) and fine-tuned afterwards that allows for 
> 320kbps audio streams inside hvf* tv files...

As you say, this example is outside the main BBC channels, and more 
specifically not a regular broadcast. I am sure you have done more 
analysis than I, but to a large extent regular broadcasts have PIDs 
beginning with b and special programmes such as Red Button or clips have 
PIDs beginning with p. In the case of Red Button programmes there is 
usually no HLS mode.  I think this is the first time I have seen a 
125kbit/s audio rate for a TV programme but that may be because when 
there has been no HLS mode I have usually used HVFxsd rather than a 
50fps mode.  That up to now has given 96kbit/s HE-AAC v1 in contrast to 
96kbit/s AAC-LC for HLShd.  The video also has some unfamiliar settings.

When you say "available on the CDN server" are you saying that different 
CDNs have different audio?  In any event a nice feature would be for 
--info to display audio settings.  As far as I am aware the iPlayer only 
offers a single audio stream, unlike satellite broadcast.

This programme was not in my cache and --info in v3.02 could not find 
it, but I was nevertheless able to download it.

As for temperatures, I read today that in south-east England it had been 
the coldest August for 30 years.  If you can spare any of your heat it 
would be very welcome!

Best wishes

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