Changes between Version 3 and Version 4 of Encode/H.265


Ignore:
Timestamp:
Oct 19, 2014, 5:24:09 PM (5 years ago)
Author:
slhck
Comment:

add more info, correct previous inaccuracies

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  • Encode/H.265

    v3 v4  
    11= FFmpeg and H.265 Encoding Guide =
    22
    3 The goal of this guide is to inform new users how to create a high-quality H.265 video using the encoder x265. '''Note:''' libx265 is under heavy development. The API may change.
     3H.265 (also known as HEVC) offers 50-75% compression efficiency compared to an H.264 video, while retaining the same quality. ffmpeg has support for HEVC encoding using the x265 encoder. '''Note:''' libx265 is under heavy development. The API may change.
    44
    5 H.265 (also known as HEVC) offers 50-75% compression efficiency compared to an H.264 video, while retaining the same quality. Similar to x264, the x265 encoder has multiple rate control algorithms, including:
     5== Getting ffmpeg with libx265 support ==
     6
     7In order to obtain a copy of ffmpeg with libx265 support, you need to build it yourself, adding the `--enable-libx265` configuration flag, with `x265` being installed on your system.
     8
     9You can also [http://ffmpeg.org/download.html download a static build], all of which bundle libx265.
     10
     11== Encoding ==
     12
     13 Similar to x264, the x265 encoder has multiple rate control algorithms, including:
    614
    715* 1-pass constant bitrate
     
    917* Constant Rate Factor (CRF)
    1018
    11 == Constant Rate Factor (CRF) ==
     19In this guide we are going with CRF encoding.
    1220
    13 In this guide we are going with CRF encoding. Use this mode if you want to retain a good quality and don't care about bitrate or filesize. It works exactly the same as in x264, so read the [[H.264]] guide for more info.
     21=== Constant Rate Factor (CRF) ===
    1422
    15 In this example, we will use the default CRF of 28, the "medium" profile, and AAC audio at 128 kBit/s. The CRF of 28 should visually correspond to libx264 video at CRF 23, but result in about half the file size. The profile determines how fast the encoding process will be – at the expense of compression efficiency.
     23Use this mode if you want to retain good visual quality and don't care about the exact bitrate or filesize. The mode works exactly the same as in x264, so please read the [[H.264]] guide for more info.
     24
     25In this example, we will use the following settings:
     26* default CRF of 28. The CRF of 28 should visually correspond to libx264 video at CRF 23, but result in about half the file size.
     27* `medium` preset. The preset determines how fast the encoding process will be – at the expense of compression efficiency. Put differently, if you choose `ultrafast`, the encode is going to run fast, but the file size will be larger when compared to `medium`. Valid presets are `ultrafast`, `superfast`, `veryfast`, `faster`, `fast`, `medium`, `slow`, `slower`, `veryslow` and `placebo`.
     28* AAC audio at 128 kBit/s. This uses the ffmpeg-internal encoder, but under [[AAC]] you will find info about more options.
    1629
    1730{{{
     
    1932}}}
    2033
    21 Generally, options are passed to x265 with the `-x265-params` argument.
     34Generally, options are passed to x265 with the `-x265-params` argument. For fine-tuning the encoding process, you can therefore pass any option that is listed in the [http://x265.readthedocs.org/en/default/ x265 documentation].
    2235
    2336== Further Info ==
    2437
    25 [http://x265.readthedocs.org/en/default/ x265 API documentation]
     38* [http://x265.readthedocs.org/en/default/ x265 API documentation]
     39* P. Hanhart et al., Subjective quality evaluation of the upcoming HEVC video compression standard ([http://infoscience.epfl.ch/record/180494/files/hanhart_SPIE2012_1.pdf PDF])