ffmpeg help - 16:9 HD -> 4:3 SD

[Braklet]

My local ATSC provider used to offer a SD simulcast on their .2 subchannel. I recorded all native SD programs from this channel since the HD stream used 4x the disk space for exactly the same program quality.

They replaced SD simulcast with some goofy Retro Television Network (aka "All Hasslehoff, All The Time").

Now I have to record the HD stream, but I'd like to convert the programs to MPEG-2 more fitting to SD content. I hope that the version of FFMPEG supplied with GB-PVR can do this odd conversion.

I plan to crop out the pillar bars and transcode the ~12Mbps stream down to something more manageable like 4Mbps.

Has anybody set up custom transcodes in GB-PVR? Any warnings before I start editing config.xml?

Can gbpvr/Third Party/FFmpeg/ffmpeg.exe accept any list of parameters I Google?

Is there a halfway decent Windows GUI front end for ffmpeg.exe that I could use for experimentation first?

Thanks in advance for any guidance!

[HtV]

This one worked ok for me:
http://www.videohelp.com/tools/gui4ffmpeg?all=1

If you have worked out a commandline you can enter it into config.xml (after backing that up ).

[Braklet]

Thanks! That link is more helpful than you know. ffmpeg.exe must be a great program since there are literally thousands of different command line parameters for the Googling; it all gets very confusing.

I tried adding a new Transcode profile to config.xml (yes I backed up ) but all I get is a zero length MPG file and no ffmpeg error codes that I can find in the logs. I definitely think I need to test various parameters before unleashing them in GB-PVR.

Next question: is there any way to remux DVR-MS programs to MPG wrappers? I currently use VideoReDo for that, but an automated utility would be better. Does anybody here have experience with AviSynth? Perhaps its DirectShow support can do the conversion.

[HtV]

maybe you want to share the transcoding profile with us. Its possible that its only a small error. FFmpeg did change some of the commandline arguments not so long ago. So its possible that the version gui4ffmpeg uses is different from the that comes with gbpvr.
You did find the ffmpeg-docs site: http://ffmpeg.mplayerhq.hu/documentation.html

I have played a little with avisynth in the past, its very powerful and configurable but also not very easy to handle.

[Braklet]

Let me try some local experimentation first. I simply Googled a parameter list someone said they used to crop pillar bars. Once I get to a point where I can test various parameters then I'll feel better about asking more detailed parameter advice. At this point I'm still nearly blind when it comes to ffmpeg.exe.

Thanks!

[HtV]

Just curious: Does gui4ffmpeg work with HD-files?

[Braklet]

You may have to wait a few days until I get time to test it out. I have already found that I have to remux my DVR-MS files to native MPG wrappers using VideoReDo in order to use the embedded GB-PVR transcoding profiles.

Once that is done, the version of ffmpeg.exe delivered with GB-PVR v1.0.16 transcodes HD MPEG-2 just fine. So at least the core executable should be OK.

[zehd]

Just curious: Does gui4ffmpeg work with HD-files?

I've noticed that when transcoding dvr-ms files to mpg, the sync really sucks. I suspect the best conversion would be to have GB-PVR to store the files already in MPEG...

ZProcess could do what you want, should you want me to add that feature...

(ZProcess isn't only all about the MVP)

[zehd]

You may have to wait a few days until I get time to test it out. I have already found that I have to remux my DVR-MS files to native MPG wrappers using VideoReDo in order to use the embedded GB-PVR transcoding profiles.

Once that is done, the version of ffmpeg.exe delivered with GB-PVR v1.0.16 transcodes HD MPEG-2 just fine. So at least the core executable should be OK.

You may look into having GB-PVR automatically transcode the DVR-MS files into MPEGS.. You will need to have a mux installed though...

[Braklet]

You may look into having GB-PVR automatically transcode the DVR-MS files into MPEGS.. You will need to have a mux installed though...

When I first installed my ATSC tuner card, I tried the two muxes that were described as supporting direct-to-MPEG-wrapper. My results were atrocious, so I ran back to the safety of DVR-MS wrappers.

The proprietary M$ format hasn't been a problem for me since I use VideoReDo to edit out commercials and remux to native MPEG file format.

A friend of mine took one of my HD DVR-MS sample clips and said that the following command line created an almost-perfect 720x480 MPEG-2 file, except that it introduced an A/V sync problem:

ffmpeg -i sample.dvr-ms -b 4000000 -vcodec mpeg2video -s 720x480 -ab 128000 -r 29.97 sample.mpg

I told him that when I remuxed with VRD, it complained about some errored audio and video frames that it corrected. Perhaps these could be responsible for the sync problem?

For the time being, I plan to run with ffmpeg to see if I can make a small batch file to do the cropping and downsample. I figure it can't hurt to at least learn more about this powerful utility.

Thanks!