How to use ffdshow postprocessing for MPEG1? [Archive]

View Full Version : How to use ffdshow postprocessing for MPEG1?

FlimsyFeet

29th October 2003, 15:11

Apparently ffdshow "can act as generic postprocessing filter for other decoders like MPEG1 or MPEG2".

I am playing a MPEG1 file in WMP 6.4, and I want to change the aspect ratio to 16:9 - can ffdshow do this?

jggimi

29th October 2003, 19:30

Good question. You should be able to test it. Run the ffdshow configurator (in your Start..Programs list), and enable MPEG1 in the codecs section, and then make your setting changes in the "resize and aspect ratio" section.

Neo Neko

30th October 2003, 00:35

IS this just something you want to do or is the file supposed to be 16:9? MPEG files often contain aspect ratio flags that cause basically all MPEG decoders to resize on playback. So if the file was encoded correctly you should not need to do this. Anyhow I have ffdshow enabled for MPEG1 and 2 respectively using libavcodec. But it does neither. :confused: Anyhow at the bottom of the list should be a selector for raw video. Which will make ffdshow insert itself in any directshow video chain.

FlimsyFeet

30th October 2003, 09:03

I tried enabling libavcodec for MPEG-1, but it wouldn't play - just a few frames and lots of corruption.

However, the raw video option did work, and yes, I could alter the AR.

The file was a "quick and dirty" analogue capture from a STB, when I couldn't use my VCR. Since the box was set to 16:9 mode, the video I captured was anamorphic 16:9. I capped at VCD res using hufyuv, encoded to MPEG-1 using TMPGEnc to burn a quick VCD to a CD-RW.

Playback on the TV was no problem - interesting - I had captured the WSS because I didn't crop the source, so the TV auto-switched to 16:9. You can actually see the signal on the line above where the picture starts. However, the encoding must have corrupted the signal because it intermittently switched back, but I could set the telly to 16:9 manually.

Now I wanted to look at the video again on my PC, and unlike MPEG-2, MPEG-1 doesn't have a DAR flag, so the picture wasn't resized and it played in "tall thin" mode inside WMP. However, setting an AR of 1:1.77 when using ffdshow solved that problem.