Transcode from Motion JPEG AVI to I-frame-only MPEG-1

blah789 · 18th December 2008, 21:31

Is it doable? Is a motion-jpeg frame identical to an MPEG-1 i-frame? If so, is there any utility that will losslessly rip each jpeg frame and place it in MPEG?
The best I could find was here
http://forums.maxconsole.net/showthread.php?t=6089
which referred to code here
http://www.codeproject.com/KB/graphi...GFunction.aspx
Unfortunately the code and the demo program are gone. Also I don't even know if the demo program could do what the thread title says (convert Motion JPEG AVI to I-frame-only MPEG-1) or if was only meant to convert one frame.

Also is this doable with MPEG-2? or MP4?

mgh · 20th December 2008, 17:33

doable with TMPGEnc. MPEG Settings-GOP structure- Iframes only. With mp4 codecs, max keyframe interval=1. You will need to set quality based encoding at close to 100% quality.

blah789 · 21st December 2008, 03:21

Before I made the post I had already tried with TMPGEnc, I-frame only. My intuition told me it would recompress, not losslessly transcode, and I was right. So I don't think that works. Here's how I know: the output differs wildly in size. It shouldn't if it were a lossless transcode (just difference in overhead for container change which tends to be minimal).

Dark Shikari · 21st December 2008, 06:38

It's theoretically possible with any 8x8DCT-based format, i.e. MPEG-1/2/4 (but not H.264).

mpucoder · 21st December 2008, 16:46

I've been holding back while trying to locate a program I found years ago and tucked away to look at later, but can't locate it in my files or online. Someone did write a program to do this, although I believe it was to mpeg-2 not mpeg-1.

As Dark Shikari noted jpeg and mpeg both use 8x8 DCT compression. Both also allow for custom quantization.
However there are two areas which present problems.
1) Jpeg allows 4 types of chroma subsampling but mpeg allows only 3:
no subsampling (4:4:4)
horizontal subsampling (4:2:2)
both horizontal and vertical subsampoling (4:2:0)
So for all except vertical only subsampling the image data can be left intact. For vertical only subsampling you would have to either upsample to 4:4:4 or downsample to 4:2:0

2) jpeg allows interlacing which is not supported at all in mpeg-1, and not equivalent to mpeg-2 field interlacing. These images would have to be fully decoded and re-encoded.

18th December 2008, 21:31	#1 \| Link
blah789 Registered User Join Date: Dec 2008 Posts: 19	Transcode from Motion JPEG AVI to I-frame-only MPEG-1 Is it doable? Is a motion-jpeg frame identical to an MPEG-1 i-frame? If so, is there any utility that will losslessly rip each jpeg frame and place it in MPEG? The best I could find was here http://forums.maxconsole.net/showthread.php?t=6089 which referred to code here http://www.codeproject.com/KB/graphi...GFunction.aspx Unfortunately the code and the demo program are gone. Also I don't even know if the demo program could do what the thread title says (convert Motion JPEG AVI to I-frame-only MPEG-1) or if was only meant to convert one frame. Also is this doable with MPEG-2? or MP4?

20th December 2008, 17:33	#2 \| Link
mgh Registered User Join Date: Oct 2004 Location: India Posts: 321	doable with TMPGEnc. MPEG Settings-GOP structure- Iframes only. With mp4 codecs, max keyframe interval=1. You will need to set quality based encoding at close to 100% quality. __________________ A shut mouth gathers no foot

21st December 2008, 06:38	#4 \| Link
Dark Shikari x264 developer Join Date: Sep 2005 Posts: 8,666	It's theoretically possible with any 8x8DCT-based format, i.e. MPEG-1/2/4 (but not H.264). __________________ Follow x264 development progress \| akupenguin quotes \| x264 git status ffmpeg and x264-related consulting/coding contracts \| Doom10

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21st December 2008, 03:21	#3 \| Link
blah789 Registered User Join Date: Dec 2008 Posts: 19	Before I made the post I had already tried with TMPGEnc, I-frame only. My intuition told me it would recompress, not losslessly transcode, and I was right. So I don't think that works. Here's how I know: the output differs wildly in size. It shouldn't if it were a lossless transcode (just difference in overhead for container change which tends to be minimal).

21st December 2008, 16:46	#5 \| Link
mpucoder Moderator Join Date: Oct 2001 Posts: 3,530	I've been holding back while trying to locate a program I found years ago and tucked away to look at later, but can't locate it in my files or online. Someone did write a program to do this, although I believe it was to mpeg-2 not mpeg-1. As Dark Shikari noted jpeg and mpeg both use 8x8 DCT compression. Both also allow for custom quantization. However there are two areas which present problems. 1) Jpeg allows 4 types of chroma subsampling but mpeg allows only 3: no subsampling (4:4:4) horizontal subsampling (4:2:2) both horizontal and vertical subsampoling (4:2:0) So for all except vertical only subsampling the image data can be left intact. For vertical only subsampling you would have to either upsample to 4:4:4 or downsample to 4:2:0 2) jpeg allows interlacing which is not supported at all in mpeg-1, and not equivalent to mpeg-2 field interlacing. These images would have to be fully decoded and re-encoded.