[FFmpeg-user] ffmpeg makes some sources darker

[Andy Furniss]

Jim Worrall wrote:
>
>> On 2016 Jan 5, at 3:13 PM, Jim Worrall <coniophora at gmail.com>
>> wrote:
>>
>>> Currently I just get an empty ffmpeg2pass-0.log and pass 1 is as
>>> slow as pass 2. As expected he result is worse as well.
>>>
>> Uh-oh, I thought that’s what was supposed to happen (except for the
>> worse result part).  I thought libx264 worked that way.  I better
>> try it the other way!
>
> I just tested doing pass both ways.  It is true that ffmpeg’s log
> appears to remain empty, while x265’s does not.  But the output is
> identical as near as I can tell, and putting pass as an ffmpeg option
> was actually slightly faster (both passes about the same speed as
> opposed to pass 1 being a bit slower via x265-params.

Hmm I just tried release x265 and with ffmpeg both my passes were the
same time, with x265-parans pass 1 was twice as fast. Quality was a bit
better min psnr wise with x265. Visually I could only really tell on the
first 10 frames - it seemed much the same after that. stats below show
that more was spent on I frames with x265-params.


ffmpeg pass 1

frame= 1461 fps=2.8 q=-0.0 Lsize=   22424kB time=00:01:00.85 
bitrate=3018.8kbits/s speed=0.116x
video:22412kB audio:0kB subtitle:0kB other streams:0kB global 
headers:1kB muxing overhead: 0.056528%
x265 [info]: frame I:      9, Avg QP:16.66  kb/s: 31133.07
x265 [info]: frame P:    331, Avg QP:17.87  kb/s: 9346.73
x265 [info]: frame B:   1121, Avg QP:22.43  kb/s: 916.00
x265 [info]: Weighted P-Frames: Y:0.0% UV:0.0%
x265 [info]: consecutive B-frames: 2.1% 0.3% 26.5% 8.2% 62.9%

encoded 1461 frames in 523.55s (2.79 fps), 3012.18 kb/s, Avg QP:21.36

ffmpeg pass 2

frame= 1461 fps=2.8 q=-0.0 Lsize=   23468kB time=00:01:00.85 
bitrate=3159.2kbits/s speed=0.116x
video:22412kB audio:1024kB subtitle:0kB other streams:0kB global 
headers:1kB muxing overhead: 0.137361%
x265 [info]: frame I:      9, Avg QP:16.66  kb/s: 31133.07
x265 [info]: frame P:    331, Avg QP:17.87  kb/s: 9346.73
x265 [info]: frame B:   1121, Avg QP:22.43  kb/s: 916.00
x265 [info]: Weighted P-Frames: Y:0.0% UV:0.0%
x265 [info]: consecutive B-frames: 2.1% 0.3% 26.5% 8.2% 62.9%

encoded 1461 frames in 523.83s (2.79 fps), 3012.18 kb/s, Avg QP:21.36

x265 pass 1

frame= 1461 fps=6.0 q=-0.0 Lsize=   22471kB time=00:01:00.85 
bitrate=3025.0kbits/s speed=0.248x
video:22458kB audio:0kB subtitle:0kB other streams:0kB global 
headers:1kB muxing overhead: 0.056320%
x265 [info]: frame I:      9, Avg QP:16.61  kb/s: 30834.66
x265 [info]: frame P:    331, Avg QP:17.90  kb/s: 9711.25
x265 [info]: frame B:   1121, Avg QP:22.56  kb/s: 818.87
x265 [info]: Weighted P-Frames: Y:0.0% UV:0.0%
x265 [info]: consecutive B-frames: 2.1% 0.3% 26.5% 8.2% 62.9%

encoded 1461 frames in 245.17s (5.96 fps), 3018.40 kb/s, Avg QP:21.47

x265 pass 2

frame= 1461 fps=2.9 q=-0.0 Lsize=   23364kB time=00:01:00.85 
bitrate=3145.3kbits/s speed=0.122x
video:22308kB audio:1024kB subtitle:0kB other streams:0kB global 
headers:1kB muxing overhead: 0.137916%
x265 [info]: frame I:      9, Avg QP:14.11  kb/s: 38589.83
x265 [info]: frame P:    331, Avg QP:17.94  kb/s: 9318.05
x265 [info]: frame B:   1121, Avg QP:22.52  kb/s: 846.47
x265 [info]: Weighted P-Frames: Y:0.0% UV:0.0%
x265 [info]: consecutive B-frames: 2.1% 0.3% 26.5% 8.2% 62.9%

encoded 1461 frames in 500.53s (2.92 fps), 2998.27 kb/s, Avg QP:21.43