Re: [Kdenlive-devel] DV NTSC is only interlaced??

[Dan D. <da...@de...>]

On Thu, Apr 28, 2011 at 7:10 PM, sean darcy <sea...@gm...> wrote:
> On 04/28/2011 12:03 AM, Dan Dennedy wrote:
>> On Wed, Apr 27, 2011 at 6:58 PM, sean darcy<sea...@gm...>  wrote:
>>> ffprobe JulyPlay2005-2005.07.24_15-06-27.dv
>>> .........
>>> Input #0, dv, from 'JulyPlay2005-2005.07.24_15-06-27.dv':
>>>    Duration: 00:04:51.55, start: 0.000000, bitrate: 28771 kb/s
>>>      Stream #0.0: Video: dvvideo, yuv411p, 720x480, 28771 kb/s, PAR 8:9
>>> DAR 4:3, 29.97 tbr, 29.97 tbn, 29.97 tbc
>>>      Stream #0.1: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
>>
>> where do you see progressive in that output? the p at the end of
>> yuv411p stands for planar.
>>
> 29.97 tbr, 29.97 tbn, 29.97 tbc :
>
> I thought this meant 29.97 fields/second and 29.97 frames/second.
> Fields/sec = Frames/sec, therefore progressive.

no, my interlaced NTSC DV shows the same values. in fact, that output
is quite confusing. That is because there are different ways to deduce
a framerate. I have to review the ffmpeg source to determine their
meaning:

tbr = AVStream.r_frame_rate
     * Real base framerate of the stream.
     * This is the lowest framerate with which all timestamps can be
     * represented accurately (it is the least common multiple of all
     * framerates in the stream).

tbn = AVStream.time_base
     * This is the fundamental unit of time (in seconds) in terms
     * of which frame timestamps are represented. For fixed-fps content,
     * time base should be 1/framerate and timestamp increments should be 1.

AVStream also has an avg_frame_rate, which shows up in ffprobe as
'fps' and I believe tries to reflect average rate of variable rate
video.

tbc = AVCodecContext.time_base

AVStream is from libavformat, and AVCodecContext is from libavcodec.

-- 
+-DRD-+