Am 08.06.15 um 17:24 schrieb Michael Niedermayer:
On Wed, Jun 03, 2015 at 04:28:48PM +0200, Christoph Gerstbauer wrote:
yes, this happens because 50mbit/sec is not correct
a max framesize of 208541 results in a bit rate of max
49.999840 mbit/sec, IIUC thats what the spec means by 50mbit/sec
The spec actually says "Up to 50Mb/s" and "Up to 208541" that being the
highest value that comes out below the the 50Mb/s. So I tend to agree
with Michael.
Hi, i have made a short excel calulation and I think that these
settings/syntaxes should be the correct ones for PAL/NTSC D-10:
Do you agree?
minrate
framerate max coded bits/byte bufsize
maxrate
framesize (Bytes)
rc_init_occupancy video bitrate
IMX50 PAL 25 250000 8 2000000
50000000
IMX40 PAL 25 200000 8 1600000
40000000
IMX30 PAL 25 150000 8 1200000
30000000
IMX50 NTSC 29,97003 208541 8 1668328
49999840,16
IMX40 NTSC 29,97003 166833 8 1334664
39999920,08
i seem to have missed this reply, my question is basicylly the same
as tims, where does the limit resulting in 39999920 come from ?
Hi, I compared different encoder IMX40 formats, and all of these format
has a pkt size of 166833bytes (=1 frame for IMX40).
-> 166833*8*(30000/1001) = 39999920bits
is there some specification that limits the VBV buffer size to a
lower value for "40mbit/sec" than "50mbit/sec" ?
Maybe I didnt understand the using of the VBV buffer?
I thought the VBV buffer size is always ONE frame. So it differs in size
when using the 50, 40 or 30 mbit format. Is this wrong?
from SMPTE S356M - 2001 - Type D-10 Stream Specifications:
" The vbv_delay parameter shall be constrained to a *1-frame* delay for
each GOP by defining the following values:
525/60 systems
– picture_header: vbv_delay = 0BBBh
625/50 systems
– picture_header: vbv_delay = 0E10h"
best regards
Christoph
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