Converting flv file from 20fps to 25fps (for DVD) - distorts Aspect Ratio

[bergqvistjl]

Hi, I have an MP4 file (originally recorded from a web stream years ago) which has a resolution of 720x406, a frame rate of 20fps and according to ffmpeg a SAR of 1:1 and a DAR or 360:203 (which displays as 16:9 when played natively).

I'm trying to use VideoReDo to encode it for DVD playback, however to do that I need to convert it to 20fps. However when I do that, it messes about with the aspect ratio & resolution (stretching it either vertically or horizontally slightly), as well as resulting in a drop in quality. Is there any way I can repair the aspect ratio into something more suitable for DVD encoding, and more importantly convert it to 25fps without losing quality? I think videoredo doesn't understand the aspect ratio and tries to compensate where none is needed and also the video quality also degrades (even on Max settings) which I would like to avoid. Maybe I should try via FFmpeg instead? The video file is here: http://mikahaksb02.srve.io/cut.mp4 I want to leave the audio track untouched.

Essentially I'd just like to convert the framerate to 25fps and the SAR and/or DAR to something more appropriate for burning to a DVD later on, while maintaining the exact same video quality (a lossless encode?) Maybe a slower framerate (one that matches NTSC) may be better?

[Baldrick]

1.1GB? Can't you make a shorter sample. Cut with makesample and see if it works.

[bergqvistjl]

1.1GB? Can't you make a shorter sample. Cut with makesample and see if it works.

OK, i've updated the OP with a new link. You should be able to use the first frame (static text) to determine quality a bit easier now anywho My previous attempts, the text (as well as everything else in the video)was blurred slighlty

[Baldrick]

You could try a good free dvd converter like avstodvd. Just convert the sample and see how it looks.

BUt I guess you need a better filter to fix the 20fps to 25fps.

[Cornucopia]

There is no getting around a drop in quality, especially when you are modifying the file so much (which requires re-encoding, to a less efficient lossy format = MPEG2).

You should let VideoReDo do the stretching it is attempting. It wants to bring the image BACK to the 720x576 anamorphic image it probably was before it got cropped & converted in the first place.
Plus, you should not be worried about the stretching, it should still play back properly. Author the title as 16:9 and all should be well. I hate to say it, but I'm pretty sure it is you who doesn't fully understand the aspect ratio.

The change in framerate (from the mangled 20fps back to its original standard rate of 25) is not so easy an adjustment and there WILL be motion irregularities no matter which method you/it uses.

Scott
(BTW, PAL-type video is assumed. If it was NTSC, it should be 720x480 @ 29.97fps)

[manono]

Even at 20fps it's a mess because there are roughly 25% of the frames that are duplicates, as well as all the missing frames. I would also see if AvsToDVD could do it (convert it to 25fps by adding duplicate frames). I think it'll get the aspect ratio correct but don't know for sure about the framerate conversion. In any event, after being converted to PAL DVD it'll play very jerky.

[_MrC_]

Tough stuff, the source clip is already quite jerky...

AVStoDVD will use a motion compensation approach with MotionProtectedFPS (http://forum.doom9.org/showthread.php?p=849558#post849558), which is better than just duplicate frames with ChangeFPS. Resulting DVD will have some blurriness, but it should prevent to become more jerky.



Bye

[bergqvistjl]

Thanks for all your help guys, I've tried it using handbrake, and that allows me to adjust the framerate while most importantly keeping the video quality identical to the original. The only problem is it won't support the LPCM audio track (It thinks it's AAC :/) Any ideas how I can get round that? Is there a way to tell it to leave the audio untouched? Will muxing it to an MKV with the audio set to FLAC, and then demuxing the MKV and decompressing the FLAC stream (to a wav I presume) do it?

[DB83]

I don't know how you think converting to an inter-mediate, and compressed, format with handbrake keeps the same quality as the original.

Just for a giggle, I took your sample and made a NTSC dvd out of it. Avstodvd defaults to ac3 but you can alter the audio to LPCM is you want. Given the type of source, the result was quite acceptable. This is version 2.4.2 which may be different to the one the author of this fine program (trust my cheque is in the post ) used.

[bergqvistjl]

I don't know how you think converting to an inter-mediate, and compressed, format with handbrake keeps the same quality as the original.

Just for a giggle, I took your sample and made a NTSC dvd out of it. Avstodvd defaults to ac3 but you can alter the audio to LPCM is you want. Given the type of source, the result was quite acceptable. This is version 2.4.2 which may be different to the one the author of this fine program (trust my cheque is in the post ) used.

I had it set to lossless conversion.

[_MrC_]

I don't know how you think converting to an inter-mediate, and compressed, format with handbrake keeps the same quality as the original.

Just for a giggle, I took your sample and made a NTSC dvd out of it. Avstodvd defaults to ac3 but you can alter the audio to LPCM is you want. Given the type of source, the result was quite acceptable. This is version 2.4.2 which may be different to the one the author of this fine program (trust my cheque is in the post ) used.

Yes, I agree: the original "quality" (whatever that word means using the uploaded sample...) cannot be retained when converting to a compressed format such as mpeg2. We can only try to avoid too much degradation.

[OT mode on] AVStoDVD 2.4.2 is quite outdated, it was released more than 3 years ago, and those kind of FPS upsizing were still done with ChangeFPS approach, hence inserting frames. You can check the latest 2.8.1 Alpha out, which has many improvements, i.e. motion compensation for FPS unusual conversion. [OT mode off]

I had it set to lossless conversion.

But PAL DVD standard need mpeg2 @ 25 fps... and H.264 to mpeg2 cannot be lossless...



Bye

[bergqvistjl]

I don't know how you think converting to an inter-mediate, and compressed, format with handbrake keeps the same quality as the original.

Just for a giggle, I took your sample and made a NTSC dvd out of it. Avstodvd defaults to ac3 but you can alter the audio to LPCM is you want. Given the type of source, the result was quite acceptable. This is version 2.4.2 which may be different to the one the author of this fine program (trust my cheque is in the post ) used.

Yes, I agree: the original "quality" (whatever that word means using the uploaded sample...) cannot be retained when converting to a compressed format such as mpeg2. We can only try to avoid too much degradation.

[OT mode on] AVStoDVD 2.4.2 is quite outdated, it was released more than 3 years ago, and those kind of FPS upsizing were still done with ChangeFPS approach, hence inserting frames. You can check the latest 2.8.1 Alpha out, which has many improvements, i.e. motion compensation for FPS unusual conversion. [OT mode off]

I had it set to lossless conversion.

But PAL DVD standard need mpeg2 @ 25 fps... and H.264 to mpeg2 cannot be lossless...



Bye

Yeah but i'm trying to create a copy of the original (in terms of quality & resolution & aspect etc) at 25FPS FIRST, and THEN upscale/re-encode it to fit on DVD after.

I'm more concerned with creating an identical copy of the original file in 25fps than worrying about getting it onto DVD right now.

[DB83]

Well handbrake in 'lossless' mode does not make an identical video stream (forget the audio for now)

Methinks you fail to understand the term 'lossless' in this scenario. It means no compression. Not an exact copy.

The enclosed attachment has been prepared with avidemux. It resamples the frame rate to 25fps and retains the PCM audio. It's still not a identical copy - the video bitrate is identical but it has 1 ref frames as opposed to the 3 in the original (I think one is better)

I have also tested this file with my old version of avstodvd and it worked just fine. VLC however would not play it but then avidemux needed all sorts of persuasion to accept PCM audio. The file has an .mp4 extension but actually is an avi mux

[bergqvistjl]

Well handbrake in 'lossless' mode does not make an identical video stream (forget the audio for now)

Methinks you fail to understand the term 'lossless' in this scenario. It means no compression. Not an exact copy.

The enclosed attachment has been prepared with avidemux. It resamples the frame rate to 25fps and retains the PCM audio. It's still not a identical copy - the video bitrate is identical but it has 1 ref frames as opposed to the 3 in the original (I think one is better)

I have also tested this file with my old version of avstodvd and it worked just fine. VLC however would not play it but then avidemux needed all sorts of persuasion to accept PCM audio. The file has an .mp4 extension but actually is an avi mux

Sorry, when I meant "identical", i meant visually, i.e. taking screencaps of the original vs the re-encoded one and comparing the two and there wern't any visible compression artefacts.

[DB83]

Well it always helps if you speak the same language as the rest of us

Visual quality is always in the eye of the beholder. Compression quality is universal.

[bergqvistjl]

OK well i've decided to quit while i'm ahead lol. I've managed to get the video to 25fps without altering the resolution or aspect, so that's as far as i'm going to risk it lol.

[DB83]

So my sample was not 'identical' ?