[mythtv-users] at dusk with the light behind it may very well pass for OnT

Mike Hodson mystica at gmail.com
Thu Jan 20 10:32:37 UTC 2022


On Thu, Jan 20, 2022 at 2:12 AM James Linder <jam at tigger.ws> wrote:

> I have a recording (not mythtv) that has missing or broken headers or time
> stamps).
> I was looking for a way to test and Klaus posted a solution, for some
> other problem, that worked for me.
> I thought his post was
>
> ffmpeg -i Channel1.20Jan2022.130000.mp4 -vcodec copy -acodec copy junk.mp4
>
> but not quite. Spelunking the man does not enlighten, and I can’t find
> that post.
> Please any suggestions
> James
>
>
Hi James,

I did a bit of searching; been on the list aaaages and have all of it saved
in my gmail since ... over a decade now. Late 2011 when I was initially
trying to setup a mythbox to record OTA for my mother.. Project was never
realized due to multiple issues of antenna and computer placement, and
being rather too far away from broadcast towers to not need some sort of
rotation on high gain directional antennas due to the variety of locations
we have broadcasting some stuff here in Denver.
Since then she passed on, yet i stay subbed since I at one point want to
try again.

To the meat of it:
Seems back in November 22-23 of 2017 in a thread titled '[mythtv-users]
video and container woes' you were having issues with an mpeg transport
stream .ts file, and the ffmpeg command to shove it into a normal mpeg
container rewriting the metadata bits was:

mythffmpeg -i /store/1017_20171001114200.ts -acodec copy -vcodec copy
-scodec copy -aspect 16:9 /store/Movies/DM8x01.mpg
[merging together a few different replies to get all the different codec
copy bits, scodec is for subtitles, which may or may not be present in a
file]

Since you are now starting with an mp4 file, outputting to a .mpg probably
doesnt make sense, you might just leave the output filename as .mp4 or
perhaps .mkv since the MKV container format is far more forgiving of any
sort of weirdness from the component streams, recording or file errors, and
other oddities than mp4 can be.  ffmpeg can put the component
streams(audio,video,subs) into whatever container you specify if it
supports it (wouldnt make sense for vorbis audio in an mpg or mp4 stream,
but you can put h264/vp9/mpeg2/etc and opus/vorbis/flac/wav/etc into an mkv
and it works. Its basically a universal container format :)

In your case today, if you have the mkvtoolnix package installed, I wonder
if using a command like:
mkvmerge -o output.mkv Channel1.20Jan2022.130000.mp4
might  do a similar job of making it play better?  Worth a try IMHO and
perhaps simpler in the future.  I find MKV files to be rather well
supported nowadays on a lot of devices.

Hope this helps!

Mike
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