[FFmpeg-devel] [PATCH 1/2] lavfi/ebur128: add support for smaller video sizes

[Marton Balint]

On Fri, 21 Nov 2014, Clément Bœsch wrote:

> (sorry for the delay)
>
> On Sun, Nov 16, 2014 at 10:53:15PM +0100, Marton Balint wrote:
>> Signed-off-by: Marton Balint <cus at passwd.hu>
>> ---
>>  doc/filters.texi        |  4 ++--
>>  libavfilter/f_ebur128.c | 11 ++++++++---
>>  2 files changed, 10 insertions(+), 5 deletions(-)
>>
>> diff --git a/doc/filters.texi b/doc/filters.texi
>> index 53f4cb2..713989c 100644
>> --- a/doc/filters.texi
>> +++ b/doc/filters.texi
>> @@ -10146,8 +10146,8 @@ activated. Default is @code{0}.
>>
>>  @item size
>>  Set the video size. This option is for video only. For the syntax of this
>> -option, check the "Video size" section in the ffmpeg-utils manual. Default
>> -and minimum resolution is @code{640x480}.
>> +option, check the "Video size" section in the ffmpeg-utils manual. The default
>> +resolution is @code{640x480}, the minimum is @code{480x102}.
>>
>
> Quoting the EBU 3341:
>  An ‘EBU Mode’ meter shall offer two scales, for when a scale is shown,
>  selectable by the user:
>  1. range -18.0 LU to +9.0 LU (-41.0 LUFS to -14.0 LUFS), named ‘EBU +9
>  scale’
>  2. range -36.0 LU to +18.0 LU (-59.0 LUFS to -5.0 LUFS), named ‘EBU +18
>  scale’
>
> When you go down to 480x102, the printed range becomes [-16;+8] LU for +9
> scale and [-32;+16] LU for +18 scale (see meter option). I think these
> range boundaries should be preserved in the output.
>

The proper range is still shown in the graph, only the legend lacks the 
value for the up and the bottom of the graph.

If you insist on showing the values for the top and the bottom of the 
graph, then in order for the lines to remain simmetrical, you will have to 
start showing rounded or non-whole values. Or if you insist on whole 
values, you may will not be able to show the lines with the same distance 
from each other.

What would be the approach you prefer in order to be able to show smaller 
graphs?

Thanks,
Marton