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| chekole |
 Posted: Mar 14 2012, 08:15 AM |
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Newbie
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Hi guys. I'm not pro on this stuff about codecs. And my english is not very good so I ask apologies in advance. I will try to explain everything.
1. I uploaded a video to youtube: http://www.youtube.com/watch?v=KBp5xD054OI
2. The original file was compressed with XVID MPEG4 Codec @ level HD 720 at the size was 48.3 MB
3. If I use Jdownloader to download the video from Youtube I can notice that Youtube converted it to MP4 extension with this codec: (720p_H.264-AAC) and the size now is 13.2 MB, the quality is almost the same as my original video but it is 3 TIMES SMALLER!!
4. I downloaded x264vfw codec.. (I dont know if that's the one that Youtube uses) and compressed my video with default settings but it is 30 MB...
So I want to know what settings does Youtube use to compress videos??? How can I get so small files with such a good quality ???? |
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| Barnister |
| Posted: Mar 14 2012, 01:36 PM |
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I use those settings to get good "HD" quality on YouTube.
http://www.donsalva.com/2009/03/01/virtual...ettings-youtube
http://www.donsalva.com/2009/09/07/fraps-v...-small-filesize
As for:
| QUOTE | | If I use Jdownloader to download the video from Youtube I can notice that Youtube converted it to MP4 extension with this codec: (720p_H.264-AAC) and the size now is 13.2 MB, the quality is almost the same as my original video but it is 3 TIMES SMALLER!! |
| QUOTE | | So I want to know what settings does Youtube use to compress videos??? How can I get so small files with such a good quality ???? |
No one knows, and there's no way to avoid re-compresion unless YouTube implements such option to allow/disallow re-compression of uploaded videos.
YouTube always will re-compress your videos, period. |
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| evropej |
| Posted: Mar 14 2012, 07:52 PM |
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I use a third party freeware software to compress them to a small file size and it works wonders. Some people get itchy though if I post names of software other than vdub. |
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| chekole |
| Posted: Mar 14 2012, 08:59 PM |
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Thank you for your answer guys, I will check your links and test settings on them.
Yesterday I uploaded a H264 video on default settings, it was 300 MB and Youtube recompressed it again to 98 MB so it is true what you say,
but I noticed that an H264 recompressed loses (a little) more quality than a XVID recompressed, in other words it gets more blur after recompress.
PS. I just read the 2 links thanks a lot now a know a little more about H264 and and virtualdub =) |
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| -vdub- |
| Posted: Mar 16 2012, 08:01 AM |
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I'm sure there are some tools that can show most of the settings the file used for encoding. I have forgotten which tools they were maybe someone here knows.
What happens if you load a video using same codecs as video site but was made to be very large high bitrate encode or other setting used. Would video site re-compress it, if so you could see settings difference from what you and they have used. And see if you can get same results.
Maybe the settings they used are always the same for certain types of videos maybe find with many tests how the video site judges whether to re-compress a video or not. |
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| chekole |
| Posted: Mar 18 2012, 12:13 PM |
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Hi guys, after uploading 4 or 5 videos on H264 these are my opinions:
1. H264 vs XVID quality is exactly the same on PC, for local use, and H264 files are 50% smaller than XVID.
1b. but when you need to fast-forward or rewind a video, XVID is better because H264 gets greenscreen and pixelated image for a few seconds.
2. For Youtube, XVID is better. After the recompress of Youtube, the H264 video losses more quality than the XVID video, it gets more pixelated, specially with red color (just like saving an image on JPG)
Thank you for your help guys. I hope that these points will help anyone on the future. |
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| -vdub- |
| Posted: Mar 19 2012, 08:51 PM |
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Did you also compare .flv from youtube I was surprise when viewed one recently 'that can't be an flv'. Then I checked under the flv hood was avc1/aac. |
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| IanB |
| Posted: Mar 20 2012, 08:53 PM |
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| QUOTE (chekole @ Mar 18 2012, 11:13 PM) | | 1. H264 vs XVID quality is exactly the same on PC, for local use, and H264 files are 50% smaller than XVID. |
Remember that both XVID and H264 are lossy compression schemes.
H264 achieves better compression than XVID by :-
1. using better techniques to analyse and compress the video and
2. having a better psycho-visual model that allows it better recognise features the human eye does not notice and delete them.
Because of 2, looking the same quality does not mean they are the same quality. Something has to go to make the file 50% smaller.
Given UTube re-compresses your video anyway I would expect better results with an input H264 source of the same size as the XVID. i.e. supply a super quality H264 source. |
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| -vdub- |
| Posted: Mar 23 2012, 10:41 PM |
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The flv clip source I viewed source was from hd from br disc. Unknown compression used when uploaded to youtube or other. Maybe youtube computer only decompressed into a flv container, is why quality remained for the video. Maybe they should do that more often and not try compress video further doing so degrading the original video quality. |
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