This is OT, so if you're offended, apologies and please ignore this e-mail!
Looking for some ffmpeg advice and comments please.
I have a Freesat box, a Humax Foxsat-HDR, which records TV programmes in
.ts format. Each video programme also has a couple of support files:
.nts files which contain the timing information required to provide
seeking, and play from last position functions on the HDR and
.hmt files which contain full details of the recording, including EPG
information
My understanding is that the video stream is mp2 (MPEG-2). The audio is
usually just the one stream, but sometimes two streams (a standard and a
narrated (NAR) stream).
I've been remuxing these recordings into MP4 format for eventual
transfer onto my NAS. I also use the AV2HDR program which reads the EPG
info so I can tag the mp4 files manually.
I've noticed that the remux process takes significantly longer than the
same process in get_iPlayer. To give an example, with giP, a one hour
programme takes less than half a minute to remux to mp4 on my PC whereas
it's rarely faster than 2x, indeed usually less than 1.0x, so films can
take some time.
I'm using a copy of the same version of ffmpeg used in gip but in its
own separate remux folder. The relevant command used is:
ffmpeg -i progname.ts -c:av copy progname.mp4
My understanding is that this should copy over the audio and video
streams unaltered but in an mp4 container. However, this does not appear
to be the case - not only does this process take significantly longer
than the gip equivalent but it's a heck of a resources hog, typically
90%+ CPU usage (negligible in gip). In addition the file sizes are
smaller with lower bitrates, so it would appear to be re-encoding in the
process. I like ffmpeg because I can top and tail my recordings by
specifying start and end times (to cut out extraneous content) while
doing the remuxing, but as it stands the remuxing time is frustrating,
to say the least, not to mention the other issues highlighted in this
e-mail.
Just wondering whether anyone can shed some light on these
discrepancies, please.
Thanks
Alan
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