[FFmpeg-user] ffmpeg makes some sources darker

[Andy Furniss]

Jim Worrall wrote:
>
>> On 2016 Jan 5, at 4:28 PM, Andy Furniss <adf.lists at gmail.com> wrote:
>>
>> 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.
>
> OK, I bow to your greater knowledge and experience, and will start
> using ‘pass’ in x265-params.  Thank you!

I snipped some other "evidence" in my last post.

If you want to check outputs between the two ways look at the last
lines of the larger block of x265 [info].

with ffmpeg the last 2 lines of both pass 1 and 2 are the same for me -

x265 [info]: tools: rd=3 psy-rd=0.30 signhide tmvp strong-intra-smoothing
x265 [info]: tools: deblock sao

with x265-params they are different and refer to reading/writing stats.

x265 [info]: tools: rd=2 psy-rd=0.30 early-skip signhide tmvp fast-intra
x265 [info]: tools: strong-intra-smoothing deblock sao stats-write


x265 [info]: tools: rd=3 psy-rd=0.30 signhide tmvp strong-intra-smoothing
x265 [info]: tools: deblock sao stats-read