HDTV specs

Jim web web at audiomisc.co.uk
Sun Mar 8 07:22:18 PDT 2015

In article <63DE2E05-1909-4722-A937-440A6D9CEF08 at cantab.net>, Owen
<owen.smith at cantab.net> wrote:
> Yes, 1280 x 720 is normal for iPlayer "HD" and they only include stereo
> sound even if the original broadcast had 5.1 sound. BBC channels
> broadcast in HD over DVB-T2 look much better, and sometimes have 5.1
> sound which I use.

OK, thanks. Confirms my suspicion that DVB-T2 is better if you can
conveniently get it!  cf below wrt some snags...

> I play all this stuff on my TV, get_iplayer downloads play fine on my
> Humax HDR Fox T2 PVR. I find watching on a PC a poorer experience for
> either iPlayer HD downloads or DVB-T2 broadcasts (I can extract them
> from my PVR).

FWIW I use the same HDTV set for viewing DVB-T/T2 and with a Linux box to
listen/view files or streams. VLC seems to me to do a good job, but I did
have to tell it to use avconv/avcodec to avoid DVB-T2 recordings of some
items having sound levels that jumped about due to 'drc' issues.

I'm particularly interested in the audio, so plan to gip some suitable item
in future for comparision with DVB-T2. Its interesting that the iplayer
files are stereo-only for the following reasons.

It seems common with DVB-T2 for the audio to switch 2 <-> 5.1. 'on the fly.
As a result when I record the streams the resulting file has such changes
at the relevant times in the file. VLC (using faad or avcodec) 'misses'
these changes. The result is that sound output falls silent. I can regain
it by re-selecting audio, and when 5.1. it is downmixed to stereo as I
require OK.

I guess that the VLC/etc developers took for granted a that a file wouldn't
ever have a change of format mid-file. So just assume that the format at
the start will define what is used thoughout the file. Alas, that's not the
case for 'raw' recordings I make from DVB-T2. :-/  This has been raised so
I'm hoping it will get fixed sometime.

MY HDTV does have a 'media player' that doesn't lose the audio at 2 <->
5.1. changes, but in other ways it is poor compared to VLC.


Electronics  http://www.st-and.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
Armstrong Audio  http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc  http://www.audiomisc.co.uk/index.html

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