Code optimisation for video
BlitzMax Forums/BlitzMax Programming/Code optimisation for video
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| I have found a difference in the smoothness of video with my code using theora as compared to the sample code provided by you for the theora module. I will be highly obliged if you could help me out on the same. My code which creates a wrapper for theora is as below. Your help is solicited. [Code] '----------------------------------------------------------------------------- ' File: TheoraMovie.bmx ' Author: Ramesh D ' Description: TheoraMovie class for playing movies in Theora Format ' Usage: To create a TheoraMovie object the Create function of TheoraMovie is called with the parameters as follows: video file path, audio file path, x position,y position, width, height '----------------------------------------------------------------------------- Import pantson.theora SuperStrict Type TheoraMovie Field _vid:Ttheora 'Field _aud:TSound Field _frameimg:TImage Field _xpos:Int Field _ypos:Int Field _width:Int Field _height:Int Field _state:Int Field _soundchannel:TChannel Const SkipVideo:Int = 1 Const EndVideo:Int = 2 Const StartVideo:Int = 3 Function Create:TheoraMovie(vidname:String,audname:String,xpos:Int,ypos:Int,width:Int,height:Int) Local mov:TheoraMovie = New TheoraMovie mov._vid=OpenTheora(vidname) 'mov._aud = LoadSound(audname) mov._xpos=xpos mov._ypos=ypos mov._width=width mov._height=height mov._state=StartVideo Return mov End Function Method ProcessInput(id:Int,x:Int,y:Int,data:Int) Select(id) Case EVENT_KEYDOWN If data=KEY_ESCAPE _state=SkipVideo Close() End If End Select End Method Method Start() _frameimg=CreateImage(TheoraWidth(_vid),TheoraHeight(_vid)) StartTheora(_vid) '_soundchannel=PlaySound(_aud) _vid.autoloop=False End Method Method Update(elapsedTime:Int) End Method Method Draw:Int() If (DrawTheoraImage(_vid,_frameimg) = True) DrawImage _frameimg,_xpos,_ypos End If Return _vid.eot End Method Method Close() 'StopChannel(_soundchannel) CloseTheora(_vid) End Method Method EndOfMovie:Int() Return _vid.eot End Method Method Pause() 'PauseChannel(_soundchannel) PauseTheora(_vid) End Method End Type '------------------------------------------------------------------------------------------------------------------------------------- 'Main loop Local m:TheoraMovie Graphics 800,600,0 ' load in movie m = TheoraMovie.Create("C:\\EAS_M.ogg","C:\\EAS_S.ogg",0,0,800,600) m.Start() ' loop until EndOfTheora While Not m.EndOfMovie() And Not KeyDown(key_escape) m.Draw() Flip Wend ' close m.Close() End [/Code] Thanking You Regards |
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| found a quick difference... my code If DrawTheoraImage(movie,image) = True Drawimage image,x,y Flip endif Your code (expanded out) If DrawTheoraImage(movie,image) = True Drawimage image,x,y endif Flip It seems that you are flipping the screen every loop, even when the image hasn't been drawn or updated. Try removing the Flip from your loop... While Not m.EndOfMovie() And Not KeyDown(key_escape) m.Draw() Wend and change your wrapper to... Method Draw:Int() If (DrawTheoraImage(_vid,_frameimg) = True) DrawImage _frameimg,_xpos,_ypos Flip End If Return _vid.eot End Method See if that makes a difference |
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| That was the problem.Thank you very much for the help. I have another problem in the same code, when the Close() method is called for the TheoraMovie Object in the middle of the movie the application crashes with memory exception error, this happens in my application but not in the example above |
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| if you turn debug on it should show you the line it crashes on. If its the DrawTheoraImage command, then you have closed the movie and then tried drawing it again (obviously this won't work) If its the CloseTheora command then I will need to investigate furthur. |
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| It gives memory exception in in the CloseTheora function, the line is _freedecoder(movie.decoder) Thanks |
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| i have tested the code again and it doesn't produce the error with me. I have a feeling that movie is already NULL when closing the file. As I don't have access to your code... can you add the following code to theora.mod can you add the following lines to mod for testing before the _freecoder(movie.decoder) line print "closing" if movie = null then print "already null" print "file = "+movie.filename you will have to re-compile the mod after (ctrl-d) the ammendment should display closing when you call the close commmand and test if its already closed. It will still error though. can you see what output the ammedment produces please? |
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| You need to use [code] in lower case for it to work. |
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| I checked the variables you mentioned at the line _freedecoder(movie.decoder). movie is not Null. movie.filename is valid movie.decoder is not Null it is Byte Ptr with some value. However movie.buffer of TBank type is allready Null at the line _freedecoder(movie.decoder). movie.file has value 000000 (all zeros) Hope that gives some clue Thanks |
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| The only time the buffer is set to null is after the _freedecoder() command. Sounds to me the close command is getting called twice. how many "closing" messages do you get? |
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| The theora movie plays fast in the VLC media player software but not in our program. How do we oprimize the speed. Your help is required. The machine specs are 1.6 GHZ with 512 MB RAM Thanks |
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| you can't VLC uses possibilities you don't have. |
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| I assume when you say The theora movie plays fast in the VLC media player software you mean the movie plays a a correct frame rate and is smooth. Theora (and MPEG, and DIVx, and Xvid and TV signals) stores the data in a YUV format. This is becuase its better for compressions and transmission than RGB. This is where the "slow" bit is.. Blitz and TheoreLib then has to convert the YUV information to an RGB environment pixel by pixel. VLC and other media players on the other hand have a special "YUV display unit" that requires no conversion. Unfotunately Blitz doesn't have YUV display capabilities and only RGB. So it will always be slow. But certainly good enough for free. (I think) |
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