[Ffmpeg-devel] [PATCH] remove drop timecode flag

Baptiste Coudurier baptiste.coudurier
Mon Apr 16 13:08:44 CEST 2007

Michael Niedermayer wrote:
> Hi
> On Mon, Apr 16, 2007 at 11:49:14AM +0200, Baptiste Coudurier wrote:
> [...]
>>>> This way the SMPTE frame ID will _roughly_ correspond to the
>>>> "hours:minutes:seconds:(1/30th seconds)" of the frame's time.  It is not
>>>> exact in NTSC, sometimes being off by up to .06 seconds.  But it does not
>>>> have an error that accumulates over time, as so is good enough for editing
>>>> and cueing, which is what it is used for.
>>> wrong it does have an error which accumulates over time and this is another
>>> reason why its a very bad idea
>>> the drop frame timecode calculation end up at 2997/100 instead of 30000/1001
>>> also what exactly is the problem with just setting the true sec/min/hour
>>> and frame within that second as mandated by mpeg4 in the mpeg2 case too
>>> if its really just an abstract ID?
>> I found this thread in mp4-tech related to mpeg4 timing:
>> http://lists.mpegif.org/pipermail/mp4-tech/2001-October/000268.html
>> Does lavc encoder use vop_time_increment_resolution, modulo_time_base
>> and vop_time_increment parameters, as mentioned ?
> your question makes no sense, the author of the mail to which you refer
> is confused, there is no drop frame, no compensation,
> no random update and no inexactness in mpeg4s timecode and timestamps

I was refering to gary's explanation obviously.

"The time of each individual VOP is governed by the
use of that time_code in conjunction with the
vop_time_increment_resolution, modulo_time_base, and vop_time_increment
parameters (along with the previously-mentioned fixed_vop_rate flag and
fixed_vop_time_increment parameter)."

I repeat my question:
Does lavc uses all those parameters mentioned for mpeg4 as mentioned ?

Is is possible to retrieve time of each individual VOP in NTSC ? That's
an interesting feature.

Unfortunately, mpeg2 was not designed like mpeg4.

Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
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