What does the output of ffmpeg mean? tbr tbn tbc etc?

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What does the output of ffmpeg mean? tbr tbn tbc etc?

steward-7


Somebody asked this question recently:

"Can someone tell me what tbr, tbn, and tbc means?"

But he also asked another question in the same message.
Apparently the other question was much more interesting to answer!

It's durn difficult to google, as every quoted FFMPEG output has it.

Please sir: What does tbr, tbc, and tbn mean?



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Re: What does the output of ffmpeg mean? tbr tbn tbc etc?

Robert Swain-2
[hidden email] wrote:

> Somebody asked this question recently:
>
> "Can someone tell me what tbr, tbn, and tbc means?"
>
> But he also asked another question in the same message.
> Apparently the other question was much more interesting to answer!
>
> It's durn difficult to google, as every quoted FFMPEG output has it.
>
> Please sir: What does tbr, tbc, and tbn mean?

There are three different time bases for time stamps in FFmpeg. The
values printed are actually reciprocals of these, i.e. 1/tbr, 1/tbn and
1/tbc.

tbn is the time base in AVStream that has come from the container, I
think. It is used for all AVStream time stamps.

tbc is the time base in AVCodecContext for the codec used for a
particular stream. It is used for all AVCodecContext and related time
stamps.

tbr is guessed from the video stream and is the value users want to see
when they look for the video frame rate, except sometimes it is twice
what one would expect because of field rate versus frame rate.

I hope that helps a little.

Regards,
Rob
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Re: What does the output of ffmpeg mean? tbr tbn tbc etc?

Horacio Sanson-3


Sunday 03 May 2009 19:20:06 に Robert Swain さんは書きました:

> [hidden email] wrote:
> > Somebody asked this question recently:
> >
> > "Can someone tell me what tbr, tbn, and tbc means?"
> >
> > But he also asked another question in the same message.
> > Apparently the other question was much more interesting to answer!
> >
> > It's durn difficult to google, as every quoted FFMPEG output has it.
> >
> > Please sir: What does tbr, tbc, and tbn mean?
>
> There are three different time bases for time stamps in FFmpeg. The
> values printed are actually reciprocals of these, i.e. 1/tbr, 1/tbn and
> 1/tbc.
>
> tbn is the time base in AVStream that has come from the container, I
> think. It is used for all AVStream time stamps.
>
> tbc is the time base in AVCodecContext for the codec used for a
> particular stream. It is used for all AVCodecContext and related time
> stamps.
>
> tbr is guessed from the video stream and is the value users want to see
> when they look for the video frame rate, except sometimes it is twice
> what one would expect because of field rate versus frame rate.
>

> I hope that helps a little.
>

I would like to get more details in the meaning of these three values (tbr,
tbn, tbc). For example what units do these parameters are and how to interpret
them??

Three examples here:

Stream #0.0(eng): Video: svq3, yuvj420p, 640x335, 24 tbr, 600 tbn, 600 tbc

Stream #0.0(und): Video: h264, yuv420p, 1280x720, 23.98 tbr, 23.98 tbn, 47.95
tbc

Stream #0.0[0xfe]: Video: h264, yuv420p, 1920x1080 [PAR 1:1 DAR 16:9], 59.94
tbr, 90k tbn, 59.94 tbc

Stream #0.0: Video: wmv2, yuv420p, 640x480, 29.92 tbr, 1k tbn, 1k tbc

What does it mean when it has a "k" at the end??  1000 fames per second? When
no PAR or DAR appear can I assume some defaults?? or can this information be
derived from the output?

I only want to get a reliable fps value of the video. For all the samples I
have the tbr seems to be the real thing.

regards,
Horacio

> Regards,
> Rob
> _______________________________________________
> ffmpeg-user mailing list
> [hidden email]
> https://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-user

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