Add ability to disable -b:v

[chekalsky]

Q	A
Bug fix?	no
New feature?	yes
BC breaks?	no
Deprecations?	no
Fixed tickets	fixes #418
Related issues/PRs	#418
License	MIT

What's in this PR?

By passing 0 to setKiloBitrate() we can bypass setting -b:v setting.

Why?

Sometimes we may prefer not to use -b:v in favor to crf.

BC Breaks/Deprecations

No BC breaks.

To Do

• Create tests

[fabienlege]

Very good idea.

I search same function so i've tested your PR but it seam that it's not working as it...
We also need to disable the 2pass mode, but I don't know how...

As it, I have this error of ffmpef :

 ffmpeg version 3.4.8-0ubuntu0.2 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 7 (Ubuntu 7.5.0-3ubuntu1~18.04)
  configuration: --prefix=/usr --extra-version=0ubuntu0.2 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-librsvg --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared
  libavutil      55. 78.100 / 55. 78.100
  libavcodec     57.107.100 / 57.107.100
  libavformat    57. 83.100 / 57. 83.100
  libavdevice    57. 10.100 / 57. 10.100
  libavfilter     6.107.100 /  6.107.100
  libavresample   3.  7.  0 /  3.  7.  0
  libswscale      4.  8.100 /  4.  8.100
  libswresample   2.  9.100 /  2.  9.100
  libpostproc    54.  7.100 / 54.  7.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/var/www/html/s2l/web/app/uploads/sites/2/2020/11/Capture-video-2020-10-01-120655-5.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: mp42mp41isomiso2
    creation_time   : 2020-10-01T10:06:10.000000Z
    encoder         : x264
  Duration: 00:00:40.00, start: 0.000000, bitrate: 239 kb/s
    Stream #0:0(und): Video: h264 (High 4:4:4 Predictive) (avc1 / 0x31637661), yuv444p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 239 kb/s, 15 fps, 15 tbr, 1500 tbn, 30 tbc (default)
    Metadata:
      creation_time   : 2020-10-01T10:06:10.000000Z
      handler_name    : VideoHandler
Codec AVOption b (set bitrate (in bits/s)) specified for output file #0 (/var/www/html/s2l/web/app/uploads/sites/2/2020/11/export-Capture-video-2020-10-01-120655-5-1080P.mp4) has not been used for any stream. The most likely reason is either wrong type (e.g. a video option with no video streams) or that it is a private option of some encoder which was not actually used for any stream.
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
Press [q] to stop, [?] for help
[libx264 @ 0x5641498b9ec0] using SAR=1/1
[libx264 @ 0x5641498b9ec0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 0x5641498b9ec0] constant rate-factor is incompatible with 2pass.
Error initializing output stream 0:0 -- Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height
Conversion failed!```

[philipp-doblhofer]

Hey,

I got the same issue as you, @fabienlege.
As described here (https://trac.ffmpeg.org/wiki/Encode/H.264#twopass), 2-pass is needed for x264, if a constant bit rate is desired (-b:v option).
The 2-pass setting is assigned here: src/FFMpeg/Format/Video/X264.php:23

Changing the getPasses() method in X264.php as following could help:

public function getPasses() {
   return $this->getKiloBitrate() == 0 ? 1 : 2;
}

[MR-AMDEV]

Guys please merge this PR so it can also be fixed in the laravel wrapper.

[Romain]

@chekalsky Thanks for this PR.
Since @fabienlege and @philipp-doblhofer identified an issue with your submission, could you change it and integrate the improvement suggested by @fabienlege?
Thanks!

[Romain]

@chekalsky I created the tests for you.
@philipp-doblhofer are you sure of your suggestion? Here is what the documentation says: There is no native or true CBR mode, but you can "simulate" a constant bit rate setting by tuning the parameters of a one-pass average bitrate encode

[chekalsky]

@Romain thank you!
@philipp-doblhofer wouldn't return $this->getKiloBitrate() === 0 ? 1 : $this->passes; be better? Is there any sense?

[philipp-doblhofer]

@philipp-doblhofer are you sure of your suggestion? Here is what the documentation says: There is no native or true CBR mode, but you can "simulate" a constant bit rate setting by tuning the parameters of a one-pass average bitrate encode

As proposed in the PR

Sometimes we may prefer not to use -b:v in favor to crf.

CRF should be used instead of a constant bitrate with -b:v.

CRF is not CBR

@chekalsky, yes that would probably be more appropriate!

[chekalsky]

@philipp-doblhofer ok, added!

[Romain]

Thanks for your contribution @philipp-doblhofer and @chekalsky !