Why mp4 or mp4.ts from identical installation?

[Charles Bradshaw]

On 11/02/17 11:31, RS wrote:

>> From: Charles Bradshaw
>> Sent: Friday, February 10, 2017 10:05 PM
>
>>>> I did, sort of, say which version of get_iplayer I'm using. If you
>>>> looked at dumps.txt.zip in my original post the last lines both say:
>>>> "get_iplayer Web PVR Manager v2.97, ©2009-2010 Phil Lewis - Licensed
>>>> under GPLv3".
>>>> ...
>>>> I think you might eventualy understand the problem if I tell you that
>>>> with get_iplayer v2.98 the problem goes away completely. Then both
>>>> installs, but still using original package manager installed with
>>>> different versions of ffmpeg, produce identical .mpg files. Albeit
>>>> ~1.4
>>>> times the size than when the intermediate is flash.
>>>>
>>>> I'm very happy that the problem has gone away, but suggest that
>>>> somebody, hopefully with a better understanding of the internals than
>>>> me, will find themselves revisiting what must be a subtle bug. :-(
>
> I am glad your problem has gone away with v2.98.  You have not said
> which mode you are using, which probably means you are using the
> default.  If that is the case, you are not comparing like with like
> between v2.97 and v2.98.
>
> In v2.97 the default is HVFsd, 960x540 50fps, with a bit rate of
> 2787kbit/s.
> In v2.98 the default is HLShd, 1280x720 25fps, with a bit rate of
> 2379kbit/s.
> Flashhd was 1280x720 25fps, with a bit rate of 2400kbit/s.
> That is the reason for the difference in file sizes.  It is not a bug.
> There is now an internal decoder for HLS and HVF.  Neither uses RTMP.
>
> As for whether the ffmpeg version was a red herring, your original
> complaint was that ffmpeg would not multiplex the .mp4.ts file to .mp4
> in one of your installations.  That installation was using ffmpeg v2.3
> when v2.5 or above was required.  If you read the release notes for
> v2.98 you will see that for the new DVF mode, if you decide to try it,
> you will need v3.0 or above of ffmpeg.

I'm not even sure I should continue this, but since you have provided me
with vital clues I will continue in the hope that we are making progress.

You don't really get it do you? I'm just a punter trying to use
get_iplayer. Just like I used to use a real to real for the radio and a
VHS recorder for TV. In that respect, I neither know nor care about
RTMP, HVFsd flash or any other of the ever increasing number of
protocols, file formats and codecs. I am probably far too old to grasp
the details of the emering mess. On the other hand I have more than 50
years experience writing, maintaining and de-bugging software. I still
do, albeit slowly these days.

I never said the file size was a bug. What I said is that 2 installs of
the same version, one working and the other not, PROBABLY contained a
SUBTLE bug.

You have explain it differently. Yes indeed, the problem is likely to do
with some perl library. But which one? My installs have 850 and 2000 odd
.pm files in respective /usr/share/perl5/vendor_perl/ CentOS installs I
do using CPAN. Specifically XML::Simple and its mirriad of deps.
Therefor the likelihood is the initially non-working install has more
recent versions. A DOWNWARD compatibility problem then, that's not
supposed to happen with perl!

All I am saying is that the ghost in get_iplayer 2.97 will probably come
back to haunt you. Somebody once said: "It's what we don't that we don't
know that matters". I have enough experience to be fairly certain that
if you pass up the opportunity to identify what it is (that you don't
know) then you will likely have to re-visit the problem later.

If my calling it a bug has offend I apologize.

If indeed we ultimately need ffmpeg v3 then there is another problem for
the average punter. Installs using anything other than the distributions
package manager is NOT a task for the faint hearted. ffmpeg is huge and
complex and hard to compile.

I ask the following because ffmpeg v3 appears to work, but I am uncertain:

Would you exepect the --ffmpeg somedir/ffmpeg command line switch work
correctely when somedir/ffmpeg is not root installed and there is
another ffmpeg and whatever its deps still present in /use/lib?

Another way of putting that is: Is ffmpeg v3 going to find its
non-installed libraries?

Please confirm the correct .get_iplayer/options file syntax for the
ffmpeg switch?

You will understand I'm just being carefull about overwriting my
installed ffmpeg.