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Old 18th April 2015, 21:03   #1  |  Link
doomleox99
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Windows BIT RATE

Hi everybody, I have a weird issue, its about MeGUI and Windows. I made an image to explain better:




I have those 2 files, the GREEN ONE and the BLACK ONE. The GREEN ONE has only video and the BLACK ONE has video and audio.

In both cases, the video is enconded with MeGUI, Preset Slower, Tune Animation and a Bit Rate of 515kbps. The audio of the BLACK file has a Bit Rate of 48kbps. I configured Windows Explorer so I can see this data in columns as you can see in the first image.

So this is the thing: WHY WINDOWS SHOWS A BIT RATE OF 514KBPS FOR THE BLACK FILE AND FOR THE GREEN ONE SHOWS 515KBPS??

YOU CAN SEE IN THE FIRST IMAGE THAT SOME OTHER FILES HAVE AUDIO, SOME OTHERS NOT, AND IN SOME CASES WINDOWS SHOWS 515 OR 514.

WHY? WHY WINDOWS SHOWS A WRONG BIT RATE SOMETIMES WHILE MEDIAINFO SHOWS THE CORRECT BIT RATE?

Thank you all for your answers.
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Old 18th April 2015, 21:24   #2  |  Link
LoRd_MuldeR
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First of all: Why do you worry so much about this? The bitrate of a video stream is almost always not a fixed thing anyway! It's fluctuating constantly. So if we talk about "the bitrate" of a video stream, what we actually mean is the stream's average bitrate. And, even in 2-Pass mode, x264 does not hit the target (average) bitrate perfectly accurate. If, e.g., you encode with a target bitrate of 515 kbps, you will almost certainly end with a slightly higher or lower average bitrate.

Code:
Creating encoder process:
x264_8bit_x64.exe --bitrate 515 --pass 2 --stats city.704x576.stats --output city.704x576.264 city.704x576.avi

ffms [info]: 704x576p 0:1 @ 60062/1001 fps (vfr)
x264 [info]: using cpu capabilities: MMX2 SSE2Fast SSSE3 Cache64 SlowShuffle
x264 [info]: profile High, level 3.1
[...]
encoded 600 frames, 92.02 fps, 514.07 kb/s
Final file size is 627.5 KB bytes.
Secondly: Why do the programs show different bitrate? Reasons I can think of include different rounding strategies ("round to nearest" vs. "truncation") when rounding from bits/s to kilobits/s. It is also quite possible that the one program simply shows the "nominal" bitrate, as stored in the fil'se header, while the other program computes the actual average bitrate of the stream. As we have seen above, this is not necessarily the same...
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Last edited by LoRd_MuldeR; 19th April 2015 at 00:25.
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Old 18th April 2015, 21:29   #3  |  Link
sneaker_ger
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MediaInfo probably just reads x264's custom SEI. So if "--bitrate 515" was used MediaInfo will show "515" regardless of whether or not the target was hit. At least that's the case for mkv because getting the bitrate right is complicated without parsing the complete file. I don't know how Windows does it.
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Old 18th April 2015, 23:37   #4  |  Link
hello_hello
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Quote:
Originally Posted by doomleox99 View Post
In both cases, the video is enconded with MeGUI, Preset Slower, Tune Animation and a Bit Rate of 515kbps. The audio of the BLACK file has a Bit Rate of 48kbps. I configured Windows Explorer so I can see this data in columns as you can see in the first image.
48 means 48kHz. It's the audio sampling rate (the number of times the audio is sampled per second), not the bitrate. Think of it in terms of CD audio or wave files. A 44.1kHz stereo wave file has a sample rate of 44.1kHz and a bitrate of 1411kbps.
If the audio is compressed, such as MP3 or AC3 etc, the bitrate and sample rate don't directly relate to each other. You can have a 128kbps/48Khz MP3 ore a 320kbps/48kHz MP3 etc.

Quote:
Originally Posted by doomleox99 View Post
So this is the thing: WHY WINDOWS SHOWS A BIT RATE OF 514KBPS FOR THE BLACK FILE AND FOR THE GREEN ONE SHOWS 515KBPS??
I assume because it's only showing the video bitrate.

Quote:
Originally Posted by doomleox99 View Post
YOU CAN SEE IN THE FIRST IMAGE THAT SOME OTHER FILES HAVE AUDIO, SOME OTHERS NOT, AND IN SOME CASES WINDOWS SHOWS 515 OR 514.

WHY? WHY WINDOWS SHOWS A WRONG BIT RATE SOMETIMES WHILE MEDIAINFO SHOWS THE CORRECT BIT RATE?
Just because you specify a particular bitrate doesn't mean you'll get exactly that birate. Being "off" by a few kbps wouldn't be unusual. How do you know MediaInfo is displaying the exact bitrate?

Try Bitrate Viewer.
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Old 19th April 2015, 00:40   #5  |  Link
doomleox99
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Quote:
Originally Posted by LoRd_MuldeR View Post
First of all: Why do you worry so much about this?
Because I have a problem (?) hahaha something related to OCD maybe.

Its probably something stupid for some people but I just wanted to know if there was a way to make Windows Explorer show 515-515-515-515-etc. I hope you get my point.


Quote:
Originally Posted by hello_hello View Post
48 means 48kHz. It's the audio sampling rate (the number of times the audio is sampled per second), not the bitrate.
No, in this case it means the bitrate of the audio I encoded for the video. But thanks for the info anyway.


Quote:
Originally Posted by hello_hello View Post
How do you know MediaInfo is displaying the exact bitrate?

Try Bitrate Viewer.
I have that program and I made some tests in the past, MediaInfo does a good job, it shows almost the same as Bitrate Viewer.

Here is an example I made for another thread in this forum:





DONT WORRY GUYS, I KNOW, ITS NOT A BIG DEAL, I WAS JUST CURIOUS.

I REALLY LIKED ALL YOUR ANSWERS, I LEARNED STUFF AND THATS GREAT! SO THANK YOU ALL!

AND THANKS FOR THE FAST ANSWERS, I REALLY APRECIATE IT!
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Old 19th April 2015, 02:43   #6  |  Link
hello_hello
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Quote:
Originally Posted by doomleox99 View Post
No, in this case it means the bitrate of the audio I encoded for the video. But thanks for the info anyway.
Yes, now I look again it even says 48kbps in your screenshot, so I'll give myself the idiot of the day award.

Last edited by tebasuna51; 19th April 2015 at 17:25.
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