Update: Progress and puzzles

[Jim Lesurf]

Another try this morning confirmed that using the --ffmpeg option lets me
have gip successfully fetch via hvfhd and convert the result into playable
mp4 files. I also spent some time with ffprobe comparing previous hvfhd
fetch results as follows.

My earliest hvfhd fetches mostly were 'silent' when played with VLC. One or
two played. The distinction seems now to be as follows:

The few where VLC played the audio had ffprobe audio stream reports like

aac (LC) mp4a/0x6134706D fltp 125k

The ones that were 'silent' *lacked* the  (LC).

The versions I then got with the --raw option as ts files gave me

aac (LC) ... etc - i.e. as the above examples where VLC *did* play the
audio. But these have ther audio as stream 0,0 whereas it is 0,1 on the
converted files above.

Examining the later mp4s converted with the new ffmpeg confirmed the
pattern that when the report included the (LC) then VLC could play the
audio, but was silent when the (LC) was absent.

Quite how this squares with what I was told by my BBC contacts I don't
know. When I find out more I may be able to resolve that.

Following on from that, a curio...

A few days ago I used Flash mode to get the old 1280x720 25fps version of
the Beriloz Romeo and Juliet (Prom 20). So I thought I'd try getting the
hvfhd version as well for comparison. A quick check on the main Proms TV
list (URL given in a previous email) showed that now Prom 20 was absent
from the list! So I could not check for any 'part' files. And a newcomer
might decide the prom wasn't available.

However the pid I'd already used (b07mlqhm) duly got me the hvfhd 50fps
version and it seems fine. Although during the end conversion gip/ffmpeg
gave a series of reports specifying a sort of 'how I am getting on' which
I've not noticed before. This gave a set of elapsed times - 4m11s 8m7s,
etc. Thinking of the 'missing segments' I have a look at playing though
some of these. Only did a few, but didn't notice any problems. So maybe
these are some kind of progress reports from ffmpeg now?

BTW Can someone say what settings/settings gip has ffmpeg use when turning
the hvfhd result from ts into mp4? Using a verbose output didn't show this
when I used gip, although I may have missed it.

Once I know,  I can expriment with it on the ts files I got earlier using
--raw to see if that creates playable mp4 that let VLC give sound OK.

With luck, this all means that when the Lumpits end and we get a flood of
delayed proms txs we can get good versions of them. Thanks again to
dinkypumpkin for making this possible! At present I doubt I'll want the
1280x720 50fps for all files. But they do improve the proms over previous
'lower spec' streams! :-)  Just a shame the BBC couldn't go to 320k aac for
the audio 8-]

Jim

-- 
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