Avoiding buffer underflow.

[jpsdr]

First, it's not an x264 problem.
I've encoded a video at average bitrate 27446kb, buffer 30000kb, max bitrate 40000kb.
I've 2 audio streams DTS-HD.
When i mux in Scenarist video with one audio stream (anyone), it's fine.
When i've tried to mux with both, i've got a buffer underflow.
So, my guess is the guilty is the max bitrate at 40000kb.
So, what is the ultimate max bitrate i can use to avoid it ?
The true edge limit value, not a very safe value.
I don't want to reduce to 35000 if 39500 would have been fine...

So, if someone know the answer, thanks in advance.

[digitalvideo]

hi,

What are the max rateof your dts hd ?
the max mux rate is 48 Mb

[Sharktooth]

there is no "true" limit. the specs says 40Mbps is the limit for the video bitrate and the max tranfer rate (video and audio) is 54Mbps.
so, my guess is the guilty is scenarist (unless you exceeded the 54Mbps transfer speed limit).

EDIT: Most softwares limit the mux rate at 48Mbps instead of 54 for safety.

[jpsdr]

hi,
What are the max rateof your dts hd ?

I don't know.
I've ripped the audio tracks from a Blu-Ray i've bought, de-noised and re-encode video, and try to remux it (for the little story).
Is there any way to know the max rate of the DTS HD ?
I must be near the limit, because error occured only at around 2/3 of the mux.
I'll try to re-encode with max video at 39Mb.

[shon3i]

EDIT: Most softwares limit the mux rate at 48Mbps instead of 54 for safety. Nope, according BD specs 48mbps is maximum for all streams together in BDAV-STD model, 54mpbs is maximum read rate @ 2x. So maximum is 48mbps and or 28mbps if you plan to burn @ 1x.

@jpsdr you need to reduce buffer, not maxbitrate.

[kolak]

DTS-HD or DTS-MA?

2x DTS-MA 5.1 24bit can go over 8mbit at peaks.

He should reduce max rate also.


Andrew

[jpsdr]

DTS-HD or DTS-MA?

.... It's different....:confused:
I've try to search a little, and on wiki find that DTS-HD is the DTS lossless concurent to THD from Dolby.
I think eac3to reported DTS-HD MA...
But, i'm a bit confused with all of this.
If i extract with eac3to the raw original video track from the Blu-Ray, is there any kind of way/tool wich can tell me the max bitrate and buffer size of the video stream ?
I mean, with around 24h to encode my video, i would like to minimise the number of tries.
Now i've started an encode reducing max br to 39000. If it doesn't work, i'll try buffer to 29000.

[mp3dom]

.... It's different....:confused:
I've try to search a little, and on wiki find that DTS-HD is the DTS lossless concurent to THD from Dolby.

I think kolak means dts-HD Master Audio (variable and lossless) or dts-HD High Resolution (constant and lossy)


I think eac3to reported DTS-HD MA...

Ok, so we're speaking of the lossless version. Are the tracks 48Khz/16bit or something else? In general a Master Audio tracks at 16bit hardly have peaks over 4 Mbps. 24bit is another matter, in general you can see peaks above 5 Mbps.


If i extract with eac3to the raw original video track from the Blu-Ray, is there any kind of way/tool wich can tell me the max bitrate and buffer size of the video stream ?

The values are probably in the header or structure of the file. If you're using Scenarist for authoring you can see both values in the properties of the file.

[jpsdr]

The values are probably in the header or structure of the file. If you're using Scenarist for authoring you can see both values in the properties of the file.
.... Yes... now that you said that, i remember having noticed this once.
I'll check this evening how the original video have been encoded.
Thanks for the tips...

Edit : According eac3to, it is DTS MA 5.1 24bits, and according scenarist, original video stream have buffer of 30MB and max bitrate of 36MB.
Edit 2 : Reducing max bitrate to 39MB was (luky) good enough...