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Frequently Asked Questions |
- What is the connection (or difference) between AviPreview made by Oliver Stephenson and AVIPreview?
- Kazaa shows that there is much more data available than it looks that your program is able to recover. Say 300Mb (~30min) out of 600Mb(~60min) is on the hard drive already, but AVIPreview plays only fraction of this (say ~15 min). What is wrong?
- Why does the processing takes so long before the file can be played?
- There are programs out there, capable of playing partially downloaded files. What is unique about AVIPreview?
- I am previewing avi files differently. Make a copy first. Fix the index and then play in my favorite player. Why should I try AVIPreview?
- Why the video is blocky during and sometime after seeking using slider?
- Could you somehow convert those encrypted Kazaa names (234532453453452345.dat) into real ones (Some_Movie.avi) while open the file? [updated]
- You have done interesting things. May I see the code?
- I downloaded your program and even put it in my Kazaa (Kazaa Lite, Morpeus) shared folder. But then I press preview in Kazaa the same black screen comes up as before. What I am doing wrong?
- I used AVIPreview to preview a file. Now got it entirely, but my favorite player shows errors (crashes) now then playing this file. I believe AVIPreview messed up my download.[new]
- AVIpreview crashes just after index regeneration.[new]
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What is the connection (or difference) between AviPreview made by Oliver Stephenson and AVIPreview?
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There is no connection except for the similar name and focus on reconstruction of broken AVI indices.
The differences? AviPreview by Oliver Stephenson writes the index at the end of the file so it can be played in your favorite player.
AVIPreview keeps the index in its own cache
(without writing anything anywhere) and able to play the file. So these are just two different approaches.
AVIPreview is a program which is able to generate the index
and play the file in a one-click fashion, without having to make a copy or write anything into the vidoe file.
The AVIPreview approach pays off especially when you want to check what is new in a file since you last time checked it
(it takes just seconds starting from alpha 0.16 version).
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Kazaa shows that there is much more data available than it
looks that your program is able to recover. Say 300Mb (~30min) out of 600Mb(~60min) is on the hard
drive already, but AVIPreview plays only fraction of this (say ~15 min)?
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There are two possible reasons:
Firstly: Kazaa downloads several file parts from several sources simultaneously, resulting in gaps
between them. AVIPreview will play only first continuous part.
Secondly: the video file was produced with errors (again gaps between video data) and AVIPreview error
correction failed to recognize this. Both this issues will be addressed in later releases.
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Why does the processing takes so long before the file can be played?
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In the current implementation, AVIPreview has to reconstruct
the index of the AVI file. Reconstruction requires AVIPreview
to perform very frequent read and seek operations on the file. This is purely a hard disk drive bound operation.
The index at the end of the AVI file was introduced in the first place to avoid this kind of processing.
There are plans to minimize and, eventually, get rid of this delay in future versions.
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There are programs out there, capable of playing partially
downloaded files. What is unique about AVIPreview?
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I am not trying to suppress the rest of the community here. There are nice
ones out there, just like with the cars: but you've got to have more choice. I
hope AVIPreview will find its niche on the market :).
As for the unique features:
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Targeted at and tested with P2P file sharing programs. Cooperation with
such programs requires some care during programming. Check the list of
supported programs on the supported software page.
If there are issues found whey will be reported either supported software
page or in the forum.
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Regeneration of the complete index, thus you get to know how much video
you have got on your HDD.
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AVIPreview very compact and not overloaded
with bunch of functions. It's probably not the most advanced player around,
but it does give you the ability to preview the content of the avi file.
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I am previewing avi files differently: I Make a copy
firstm then fix the index, and lastly play it in my favorite player. Why should I try
AVIPreview?
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Pretty much answered in the first Q/A.
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Why the video is blocky during and sometime after seeking using slider?
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There are two types of video frames in an AVI. Ordinary frames and Key frames.
A Key frame has enough information to decode a full frame of a video stream.
Ordinary frames only have information about changes that happen in the video from
frame to frame. For proper decoding, a player always has to start from a Key frame.
If there is no indication of which frame is the Key frame, the player
starts from the current frame, which is generally not a Key frame.
The index generation algorithm is very simple - AVIPreview
has not been implemented with a Key frame search function yet. Thus, AVIPreview
treats all frames equally. So playback will look weird until a Key frame is played - then everything
will play normally again.
This issue will be addressed in future releases.
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Could you somehow convert those encrypted Kazaa names (234532453453452345.dat) into real ones (Some_Movie.avi) while the file is open?
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An upgrade for AVIPreview is here!
Click to get your copy
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You have done interesting things. May I see the code?
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Sorry, AVIPreview is not open source.
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I downloaded your program and even put it in my
Kazaa (Kazaa Lite, Morpeus) shared folder. But then I press preview in Kazaa the same black
screen comes up as before. What I am doing wrong?
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Not a thing! The thing is, AVIPreview is not integrated
with Kazaa/Kazaa Lite, so Kazaa keeps calling its internal player (WM). The way I use the program is the following:
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First, you have to know the location of the folder where Kazaa puts downloaded files. In Kazaa, go to
Tools->Options and click Traffic. There is a field "Folder for downloaded
files", so this is where all your dowloads are, go to that folder.
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Kazaa keeps its downloads in files with a '.dat' extension. Each download = one dat file.
You open those files using AVIPreview:
whichever way suits you better: File-Open, drag-n-drop, double click (if you associated .dat
extensions with AVIPreview), Open with, etc.
The trick is to know which dat file corresponds to which download.
- In Morpheus, just associate AVI/MPG extensions with AVIPreview - this seems to do the trick.
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I used AVIPreview to preview a file.
I've downloaded the whole file, but my favorite player shows errors (crashes) when I try to play it.
I believe AVIPreview messed up my download.
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There are a lot of broken movies out there - that is why there are so many utilities to fix them ;).
In all cases of "broken files", AVIPreview was likely not the culprit.
A number of users do accuse AVIPreview ruining their files, so my
suggestion is to download the file again but to do so without using AVIPreview.
Then compare both copies. In ALL cases both files were IDENTICAL, so the ORIGINAL file turned up to be broken.
Moreover, in some cases I downloaded those problematic files to my computer (again not using
AVIPreview) and they were broken in the same spots (time instants, frames)
as the other people were complaining about. So I honestly believe AVIPreview is not damaging
downloaded video files in any way.
If there is an error in a file, AVIPreview cannot regenerate the index
beyond that point and stops playback.
Besides, AVIPreview opens the file ONLY for READ operations;
it does not perform any modifications to the file in any way. And since it works only with the usable
(already downloaded parts) of the file, and P2P/FTP applications write the data at the end/empty spots,
they should not disturb each other.
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AVIPreview crashes just after index regeneration.
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In majority of the cases that would be attributed to the buggy Ffdshow filter.
Please do read this thread on the forum
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