[mythtv-users] H264 conversion of interlaced MPEG2?

John Pilkington J.Pilk at tesco.net
Tue May 12 10:29:07 UTC 2015


On 12/05/15 10:17, Mike Perkins wrote:
> On 12/05/15 02:49, Michael Stucky wrote:
>> On May 11, 2015 4:17 PM, "Jay Foster" <jayf0ster at roadrunner.com> wrote:
>>>
>>> On 5/11/2015 12:46 PM, Michael Stucky wrote:
>>>>
>> <deletia>
>>>> Sorry for the delay, it was a busy weekend+... I am not an ffmpeg
>>>> expert
>> so all the syntax came either from the original shell script or searches
>> for a better way to deinterlace. But I have done some additional
>> searching
>> and testing have updated my script on the wiki accordingly.
>>>>
>>>> "yadif=1" has become "yadif=0:-1:1" (mode 0 = one frame out for one
>> frame in, parity -1 = autodetect, and deint 1 = only deinterlace frames
>> marked as interlaced). "sws_flags spline" is removed (only applies when
>> scaling content?). "-r 60000/1001" is removed (this actually caused every
>> frame to be duplicated for interlaced content). "threads 0" is removed
>> (the
>> h264 encoder uses all available threads by default). "-c:a copy" replaced
>> with "-strict -2" to use the internal AAC encoder.
>>>>
>>>> This works and produces good quality output for all my content, 1080i,
>> 720p, and 480i all OTA to HDHomerun tuners.
>>>>
>>>
>>> I took a look at the script on the wiki and had a question.  Does this
>> break commercial skipping?  The script does not appear to reschedule a
>> commflag job after the transcoding.
>>>
>>
>> The script was designed to prepare a recording for export to the Video
>> Library where it can be played by different players/devices (vlc,
>> mplayer,
>> android, ios, etc.). As such commercial skipping wasn't a consideration.
>> The script will remove a cutlist if it exists (so
>> leaders/trailers/commercials should all be automatically removed
>> before the
>> transcoding takes place).
>>
>> If it is helpful, please take the script and modify it to do what you
>> want
>> it to and create a new wiki page for your script so we all can benefit
>> from
>> it!
>>
> A tricky one. Normally you'd edit the file - or commflag it - before
> processing so you only processed the parts you wanted.
>
> However, with the likely changes in the stream when commercial /
> trailers / etc interrupt the program commflagging is not as perfect as
> it was in the analog days.
>
> Preprocessing first into a uniform stream does at least give the
> commflag process a fighting chance, though whether you need to
> post-process to rebuild seek references (I didn't say seek tables, I
> know they're not used with h264) is an interesting question.
>

But assuming that Mike S's updated script does what his comment says 
(and if it doesn't apply the cutlist), surely
" "yadif=0:-1:1" (mode 0 = one frame out for one frame in,"
implies that a surviving cutlist would retain its original validity?

I'm afraid I haven't tested this :-)




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