Explorer wrongly displays bit rate

[Terry Pinnell]

I've just added the Bit Rate column to an XP Explorer folder. Seemed a
potentially convenient way of displaying it while I experiment with
various video file conversions. But it doesn't seem to make any sense. For
the test file in my screenshot it shows 705 kbps (0.7 Mbps) instead of
around 40 Mbps reported by VirtualDub, MediaInfo and VLC. That's out by a
factor of around 60!

http://dl.dropbox.com/u/4019461/BitRatePuzzle-Explorer-1.jpg

I tried several other AVI files from various sources, with similar
results.

 

[Rob]

I've just added the Bit Rate column to an XP Explorer folder. Seemed a
potentially convenient way of displaying it while I experiment with
various video file conversions. But it doesn't seem to make any sense. For
the test file in my screenshot it shows 705 kbps (0.7 Mbps) instead of
around 40 Mbps reported by VirtualDub, MediaInfo and VLC. That's out by a
factor of around 60!

http://dl.dropbox.com/u/4019461/BitRatePuzzle-Explorer-1.jpg

I tried several other AVI files from various sources, with similar
results.

You are looking at different things - this should help:
http://en.wikipedia.org/wiki/Bit_rate

 

[Terry Pinnell]

You are looking at different things - this should help:
http://en.wikipedia.org/wiki/Bit_rate

Thanks Rob, but I don't follow. What is different? (Apart from the units
in one case being kbps and the other Mbps?)

 

[Rob]

Thanks Rob, but I don't follow. What is different? (Apart from the units
in one case being kbps and the other Mbps?)

If I read your original post correctly, the bitrate shown by explorer
is the actual rate of the completed encoded stream, whereas the figures
you see in vDub etc are the (real time) rate at which they are actually
doing the encoding?
The rate seen in the final file (705kbps) is what the playback system
needs to be able to provide as a minimum to avoid 'stuttering'.

However, I don't know what sort of video formats you are using, so
could well be wrong! 40Mbps would be the maximum for video encoded
to Blu-ray format standard, for example. If that's the sort of thing
you are doing, then you may well be right that explorer isn't showing
the correct rate.
As XP pre-dates most modern video standards, it simply won't understand
the fourcc codes used in some media file headers, so you really do need
to use something like MediaInfo. I don't know if XP is capable of using
installed codecs to determine this - if so, it may be that there is a
codec issue. Things go a bit dim inside Windows when it comes to codecs!

Cheers,

 

[Patok]

I've just added the Bit Rate column to an XP Explorer folder. Seemed a
potentially convenient way of displaying it while I experiment with
various video file conversions. But it doesn't seem to make any sense. For
the test file in my screenshot it shows 705 kbps (0.7 Mbps) instead of
around 40 Mbps reported by VirtualDub, MediaInfo and VLC. That's out by a
factor of around 60!

http://dl.dropbox.com/u/4019461/BitRatePuzzle-Explorer-1.jpg

I tried several other AVI files from various sources, with similar
results.

A bit rate of 705kbps is about right for non-HD video encoded with
not too high quality setting. Encoding clips taken from DVD to AVI files
using the XVID codec, for example, can yield 1.5 to 2.0 Mbps, if you
insist on higher quality. As Rob writes, 40Mbps is only for HD at
highest quality. The suspect figure in your case is the 40Mbps, not the
one in your screenshot.
Using VirtualDub, open the encoded file - that same sample clip - and
do File -> File Information... Is the Video stream Data rate 40Mbps? I'm
betting it will be 705kbps, or close.

 

[Terry Pinnell]

If I read your original post correctly, the bitrate shown by explorer
is the actual rate of the completed encoded stream, whereas the figures
you see in vDub etc are the (real time) rate at which they are actually
doing the encoding?
The rate seen in the final file (705kbps) is what the playback system
needs to be able to provide as a minimum to avoid 'stuttering'.

However, I don't know what sort of video formats you are using, so
could well be wrong! 40Mbps would be the maximum for video encoded
to Blu-ray format standard, for example. If that's the sort of thing
you are doing, then you may well be right that explorer isn't showing
the correct rate.
As XP pre-dates most modern video standards, it simply won't understand
the fourcc codes used in some media file headers, so you really do need
to use something like MediaInfo. I don't know if XP is capable of using
installed codecs to determine this - if so, it may be that there is a
codec issue. Things go a bit dim inside Windows when it comes to codecs!

Cheers,

Thanks for the follow-up. From further research it turns out that 'Bit
rate' in Explorer means 'AUDIO Bit rate'! Looks correct for the examples
I've tried.

 

[Terry Pinnell]

A bit rate of 705kbps is about right for non-HD video encoded with
not too high quality setting. Encoding clips taken from DVD to AVI files
using the XVID codec, for example, can yield 1.5 to 2.0 Mbps, if you
insist on higher quality. As Rob writes, 40Mbps is only for HD at
highest quality. The suspect figure in your case is the 40Mbps, not the
one in your screenshot.
Using VirtualDub, open the encoded file - that same sample clip - and
do File -> File Information... Is the Video stream Data rate 40Mbps? I'm
betting it will be 705kbps, or close.

Thanks, but afraid you'd have lost your bet! ;-)

See my reply to Rob.

The figures I reported were for HD, correctly reported elsewhere as around
40 Mbps. The Explore figure is the audio bit rate.