Recherche avancée

Sur d’autres sites (13771)

• How to encode a stream of RGBA values to video ?

  20 septembre 2011, par Rob Oplawar

  More specifically :
  I have a sequence of 32 bit unsigned RGBA integers for pixels- e.g. 640 integers per row starting at the left pixel, 480 rows per frame starting at the top row, repeat for n frames. Is there an easy way to feed this to ffmpeg (or some other encoder) without first encoding it to a common image format ?

  I'm assuming ffmpeg is the best tool for me to use in this case, but I'm open to suggestions (the output video format doesn't matter too much).

  ---

  I know the documentation would enlighten me if I just knew the right keywords... In case I'm asking the wrong question, here's what I'm trying to do at the highest level :

  I have some Actionscript code that draws and animates on the display tree, and I've wrapped it in an AIR application that draws BitmapData frame-by-frame. AIR has proved to be woefully inefficient at directly encoding this output- the best I've managed is a few frames per second, and I need to render at least 15 fps, preferably more like 100 fps, which I get out of ffmpeg when I feed it PNG images (AIR can take 1+ seconds to encode one 640x480 png... appalling). Instead of encoding inside AIR I can send the raw byte data out to an encoder or to disk as fast as it's rendered.

  If you're wondering why I'm using Actionscript to render an animation or why it has to be encoded quickly, don't. Suffice it to say, the frames are computed at execution time (not stored as an animation in a .swf file, for example), I have a very large amount of video to create and limited time to do so, and using something other than Actionscript to produce the frames is not an option.

• Decode h264 video

  29 août 2011, par john bowring

  I am looking for a way to decode h264 (or indeed any video format) using c#. The ultimate goal is to be able to decode the images and very strictly control the playback in real time. The project I am working on is a non-linear video art piece where the HD footage is required to loop and edit itself on the fly, playing back certain frame ranges and then jumping to the next randomly selected frame range seamlessly.

  I have created an app which reads image files (jpegs) in from the disk and plays them on screen in order, I have total control over which frame is loaded and when it is displayed but at full HD res it takes slightly longer than I want to load the images from hard drive (which are about 500k each), I am thinking that using a compressed video format would be smaller and therefore faster to read and decode into a particular frame however I cannot find any readily available way to do this.

  Are there any libraries which can do this ? i.e. extract an arbitrary frame from a video file and serve it to my app in less time than it takes to show the frame (running at 25fps), I have looked into the vlc libraries and wrappers for ffmpeg but I don't know which would be better or if there would be another even better option. Also I don't know which codec would be the best choice as some are key frame based making arbitrary frame extraction probably very difficult.

  Any advice welcome, thanks

• Decode h264 video with csharp

  28 août 2011, par john bowring

  I am looking for a way to decode h264 (or indeed any video format) using c#. The ultimate goal is to be able to decode the images and very strictly control the playback in real time. The project I am working on is a non-linear video art piece where the HD footage is required to loop and edit itself on the fly, playing back certain frame ranges and then jumping to the next randomly selected frame range seamlessly.

  I have created an app which reads image files (jpegs) in from the disk and plays them on screen in order, I have total control over which frame is laoded and when it is displayed but at full HD res it takes slightly longer than I want to load the images from hard drive (which are about 500k each), I am thinking that using a compressed video format would be smaller and therefore faster to read and decode into a particular frame however I cannot find any readily avaiable way to do this.

  Are there any libraries which can do this ? i.e. extract an arbitrary frame from a video file and serve it to my app in less time than it takes to show the frame (running at 25fps), I have looked into the vlc libraries and wrappers for ffmpeg but I don't know which would be better or if there would be another even better option. Also I dont know which codec would be the best choice as some are keyframe based making arbitrary frame extraction probably very difficult.

  Any advice welcome, thanks