Article Date: January 30, 2005

MediaTech @ Lyberty.com : BitRate Checking

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This is an example of checking the file format details using different applications.

File to be checked:

C:\Documents and Settings\lyberty\My Documents\My Videos\tv\new-disk-history\AlmanacHeavenonEarthJudaism-158660-0.mpg

While I'm watching the bitrate, the results are all over the place: 4400, 4270, 3380, 4505 . . .

Now, based on output of 'MPEG Validator',   4 400 000 kilobits per second   isn't the average, it's the PEAK:

Average Bitrate = 2928 Kbps
Peak Bitrate (1 sec) = 4899 Kbps

But for some reason, the File Header identifies the bitrate as "6075 kbps"; see System Bitrate ("Sys Bitrate") in the following image:

GSpot ~ Summary : 720x480 MPEG-2 @ 4400 kbps (variable); MP-2 (MPEG-1 Layer 2) audio @ 48 kHz (384 kbps) (kilobits per second)

DVD Patcher ~ Summary : 720x480 MPEG-2 @ 4296.9 kbps; no audio info

Nero Showtime ~ Summary : 720x480 MPEG-2 @ 3380 kbps (variable); non-specified MPEG audio @ 384 kBps (kiloBytes? i think this is a typo)

covert 3.3 megabits to kilobits: 3.3 megabits = 3, 379.2 kilobits

MPEG Identifier ~ Summary : 720x480 ? @ 4505.6 kbps ; no audio data
This one's not very useful. No audio data, and very limited video data.

 

The Winner: MPEG-2 Validator

Video
MPEG-2 Program Stream
Frame Type = Interlaced
Average Bitrate = 2928 Kbps
Peak Bitrate (1 sec) = 4899 Kbps
Audio
MPEG; Layer = 2 ; bitrate = 384 Kbps ; Frequency = 48000 Hz;
MPEG file size 787.46 MB

Here's instructions from the program author:

To obtain a proper diagnostic you need, before analysis, set up the configuration file: MPEGReference.ini

The values of all parameters follow the ISO 31818 spec. For example:
Frame rate = 29.97 is represented by: 'FrameRate=4'

An aspect ratio of 16/9 by: 'AspectRatio=3'

and so on.

If you don't change MPEGReference.ini will obtain as resutl: Failed! every time.

Regards,

Gabriel

PS: This version of MPEG Validator only support MPEG legacy media, ie, audio AC-3 give us: NO AUDIO

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For the MPEG2 standards you'll want ISO13818-1 (Systems), ISO13818-2 (Video), and ISO13818-3 (Audio) [aka ISO/IEC 13818]

Note that 1996 version was replaced by the 2000 version
Title: "Information technology -- Generic coding of moving pictures and associated audio information: Systems"
Overview/Summary is available here

It is the same standard as:

ITU H 222.0 (ISO31818-1,systems) {standard is jointly referred to as ITU-T Rec. H.222.0 | ISO/IEC 13818-1 } , and
ITU H.262 (ISO31818-2, video)

 

ITU let you download up to three standards for free from their website....

As for (ISO31818-2, audio), there are various drafts of it floating about;
search on google.

See also ETSI EN 300468

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other standards documentation:
ISO: Overview of the MPEG-4 Standard (2000) [html] | Word format [.doc]

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My VideoHelp.com Review: (see also Video Bitrate Calculators )

While this program doesn't actually validate your MPEGs, the amount of info it gives you makes it a much better program than any of the other files listed at videohelp.com under "Video Identifiers".

In addition to the standard info (resolution, frames per second), it tells you, for example, whether your source file is interlaced or not, average bit rate, peak bit rate, frame info, detailed stream type (e.g. "Stream Type = MPEG-2 MP@ML VBR"), chroma format, detailed GOP data, and so on. Plus it has equally detailed info for the Audio stream, including a very nice graphical bit rate analyzer (bit rate chart).

[ This part of the program is an excellent graphic representaiton of data, beating other aps like 'DVD Bit Rate Viewer' hands down.
See http://www.lyberty.com/mediatech/format-check.htm for a screen shot.]

Sure, the info could have been arranged more nicely, but then the designer would have to decide what info NOT to show you (See, for example, VideoInspector).

Personally, I'd much rather have an accurate average bit-rate value than a user interface.
(A common problem with the "prettier" programs is that they were designed for AVI files, and frequently give inaccurate
bit rate info.)

For getting file data, I'd recommend this program over GSpot, DVD Patcher, MPEG Identifier, etc.

If anyone know of another program that gives as much data AND gives accurate average bit rate info, I'd like to know what it is....

I'd also recommend that the Program Author put up a Donate button on his web page, as this program is definitely worth
at least a couple of bucks (I'd probably pay $5 to $8 for it...)

 

MPEG-1 Audio (ISO/IEC 11172-3) provides single-channel ('mono') and two-channel ('stereo' or 'dual mono') coding at 32, 44.1, and 48 kHz sampling rate.
The predefined bit rates range from 32 to 448 kbit/s for Layer I, from 32 to 384 kbit/s for Layer II

Some inexpensive DVD recording software programs use MPEG audio, even on NTSC discs, which goes against the DVD standard and is not supported by all NTSC players.
In other words, for NTSC, the audio is supposed to be Linear PCM (LPCM) or Dolby Digital (AC-3).
But there are actually 4 DVD compliant audio streams: AC3, LPCM, MP2 and DTS.

For stereo output (analog or digital), all players have a built-in 2-channel Dolby Digital decoder that downmixes from 5.1 channels (if present on the disc) to Dolby Surround stereo.

What is MP3?
Originally, the file extension ".mp3" was created with the emergence of MPEG-1 Layer III encoder and decoder software for Windows.
After standardisation of MPEG-2, sound files encoded with the MPEG-2 lower sampling rate extension of Layer III are also called "MP3"-files. Sometimes MP3 is wrongly called MPEG-3.
(So "MPEG-1 Layer 2" audio could be abbreviated as "MP2"....)

Nero Digital Info/AAC

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Try my Video Bitrate Calculator (web based: It's not very good ; it was more an experiment to see if I could get the javascript to work... You should
double check any results you get out of it.)

Feedback?

This page first posted: January 30th, 2005
File Modified: 2005-11g-03 (November 3rd, Thurs, 2005, 12:00am)
File Size: 9.33 KB (9,559 Bytes)
Author: Lyberty