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Old 14th June 2015, 17:52   #1  |  Link
reigan42
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x264 lossless and presets

Hi, i'm using footage from an hdpvr2 that has x264/aac in m2ts container and I was wondering does it negatively affect quality in lossless x264 to use ultrafast preset over slower?
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Old 14th June 2015, 18:24   #2  |  Link
foxyshadis
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Lossless is lossless. Only size and speed changes with presets.
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Old 14th June 2015, 18:30   #3  |  Link
reigan42
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Thanks that helps me out alot
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Old 15th June 2015, 08:21   #4  |  Link
neil wilkes
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Quote:
Originally Posted by reigan42 View Post
Hi, i'm using footage from an hdpvr2 that has x264/aac in m2ts container and I was wondering does it negatively affect quality in lossless x264 to use ultrafast preset over slower?
Yes it does make a difference.
There is no such thing as lossless 264 - it's a data reduced codec.
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Old 15th June 2015, 08:51   #5  |  Link
vivan
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Quote:
Originally Posted by neil wilkes View Post
There is no such thing as lossless 264 - it's a data reduced codec.
Of course there's - H.264 has special profile that supports all features needed for lossless encoding (which x264 of course supports).
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Old 2nd July 2015, 03:31   #6  |  Link
F J Walter
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Quote:
Originally Posted by neil wilkes View Post
Yes it does make a difference.
There is no such thing as lossless 264 - it's a data reduced codec.
As mentioned, h.264 has features that allow for lossless encoding but few encoders support it, but x264 does. In x264 it's activated by setting QP to 0. When used, the video is encoded so that it can be decoded to a result that is bit-identical with the source of same chroma resolution. It switches to a special lossless macroblock coding mode where QP is not actually relevant, but it still benefits from the motion estimation searches, reference frames and so forth.
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