Discussion Forums > Technology
Epic IY Encoding Fail (Help would be much appreciated! :])
Daiz:
--- Quote from: blubart on April 09, 2010, 11:40:29 AM ---(crf requires only one pass with only a marginally worse compression ratio compared to 2pass).
--- End quote ---
Actually it is not worse at all. The only thing that might be better than CRF alone is CRF first-pass with the target encoding settings (and obviously --slow-firstpass) and then doing a second pass using the final bitrate from the CRF encode, but even then the difference would be basically nonexistent. Any extra quality that you think 2-pass might give is basically purely placebo.
--- Quote ---#x264 @ Freenode, 25th of February, 2010:
[17:43:35] <vlt> Hello. I want to encode some videos to h.264/avc. I don't care for an _exact_ file size or bitrate, so I'd use "--crf". Is it always better to use multipass encoding, i. e. will a multipass encoded video w/ the same _avg_ bitrate look better than the crf-encoded one?
[17:44:41] <Dark_Shikari> vlt: no it won't
[17:44:48] <Dark_Shikari> within margin of error.
[17:44:51] <Dark_Shikari> last test I did, crf won slightly
--- End quote ---
(Dark_Shikari is one of the leading developers of x264, just to note).
--- Quote from: Takeshi on May 10, 2010, 10:18:03 AM ---Funny facts:
I've done a 2-automated encode of Battle Royale I which lasted for 2x8 hours of pure encoding = a 1,26 GB file.
I've done a CRF16 encode of Battle Royale II which lasted for 9-10 hours of pure encoding = a 2,21 GB file.
Either there was a big demand of quality because of high-motion scenes in the second movie as opposed to the first one or this CRF has a bad compression ratio.
--- End quote ---
For live-action material, I'd say that CRF 16 is quite overkill. It's good for animated material, but for live-action DVD material I'd start from 18 and go up from there.
To determine a good CRF for yourself, the best approach would be to cut some intensive scenes together and encode that part many times while raising the CRF until you hit the highest CRF value where you are pleased with the visual quality. Then you encode the whole thing with that CRF.
Takeshi:
--- Quote from: Daiz on May 10, 2010, 12:15:46 PM ---
--- Quote from: Takeshi on May 10, 2010, 10:18:03 AM ---Funny facts:
I've done a 2-automated encode of Battle Royale I which lasted for 2x8 hours of pure encoding = a 1,26 GB file.
I've done a CRF16 encode of Battle Royale II which lasted for 9-10 hours of pure encoding = a 2,21 GB file.
Either there was a big demand of quality because of high-motion scenes in the second movie as opposed to the first one or this CRF has a bad compression ratio.
--- End quote ---
For live-action material, I'd say that CRF 16 is quite overkill. It's good for animated material, but for live-action DVD material I'd start from 18 and go up from there.
To determine a good CRF for yourself, the best approach would be to cut some intensive scenes together and encode that part many times while raising the CRF until you hit the highest CRF value where you are pleased with the visual quality. Then you encode the whole thing with that CRF.
--- End quote ---
So CRF16, as blubart pointed out, is the max CRF for anime. And CRF18, for example, will decrease the bitrate used, but will still divide its bitrates based on the scenes in the given anime or live-action?
I don't have a high-end pc to encode on so it takes quite a while for me to see some results. How much a difference is there between CRF18 and CRF23? I noticed that meGUI's CRF setting was set on 23 as default. I still have the impression that 2-pass encodes gives a better result + a smaller filesize.
But I gotta say, I find CRF more appealing in terms of how long it needs to encode. A 100min anime movie is only taking me 9 hours as opposed to the 1 day per pass.
Though I still have to figure out how to encode only cutted scenes.
I find it weird that you can't demux an audio stream, and then choose not to re-encode. No, you have to re-encode it according to meGUI. Forces me to demux no audio streams and then just demux when the encode is done and mux with mkvmerge. Logical since I want the original audio stream to add to my video encode, and not something meGUI wanted to re-encode....
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