A JPEG movie file consists of a header followed by a sequence of JPEG-compressed images followed by one or more sound tracks. It responds to a subset of the protocol for MPEGFile so that a JPEG movie can be played by MPEGDisplayMorph as if it were an MPEG movie.

	file ops
	closeFile fileHandle fileName openFileNamed:

	initialization
	initialize

	private
	bytesForFrame: readHeader testPlay

	video
	hasVideo videoDropFrames:stream: videoFrameHeight: videoFrameRate: videoFrameWidth: videoFrames: videoGetFrame: videoReadFrameInto:stream: videoSetFrame:stream:

	movie creation-private
	updateFrameOffsets:on: updateSoundtrackOffsets:frameOffsets:on: writeFrame:on:quality:displayFlag: writeFramesFrom:on:quality: writeHeaderExtent:frameRate:frameCount:soundtrackCount:on: writeSoundTracksFrom:on:

	testing
	isJPEGMovieFile:

	audio	top
	audioPlayerForChannel: Answer a streaming sound for playing the audio channel with the given index.
	hasAudio Answer true if this movie has at least one sound track.

	file ops	top
	closeFile Close my file stream.
	fileHandle Answer my file, or nil if the file is not open.
	fileName Answer the name of my file.
	openFileNamed: Open the JPEG movie file with the given name.

	initialization	top
	initialize

	private	top
	bytesForFrame: Answer a ByteArray containing the encoded bytes for the frame with the given index. Answer nil if the index is out of range or if my file is not open.
	readHeader Read a JPEG movie header file.
	testPlay Performance benchmark. Decompress and display all my frames. Answer the frame rate achieved in frames/second. No sound is played.

	video	top
	hasVideo Answer true if I have one or more frames.
	videoDropFrames:stream: Advance the index of the current frame by the given number of frames.
	videoFrameHeight: Answer the height of this movie.
	videoFrameRate: Answer the frame rate of this movie.
	videoFrameWidth: Answer the width of this movie.
	videoFrames: Answer the number of video frames in this movie.
	videoGetFrame: Answer the index of the current frame, or zero if the movie has no frames.
	videoReadFrameInto:stream: Read the next frame into the given 16-bit or 32-bit Form.
	videoSetFrame:stream: Set the index of the current frame.

	movie conversion	top
	convertMPEGFileNamed:toJPEGMovieNamed:quality: Convert the MPEG movie with the given file name into a JPEG movie with the given file name.
	convertSqueakMovieNamed:toJPEGMovieNamed:quality: Convert the Squeak movie with the given file name into a JPEG movie with the given file name.

	movie creation-private	top
	updateFrameOffsets:on: Update the JPEG movie file header on the given stream with the given collection of frame offsets.
	updateSoundtrackOffsets:frameOffsets:on: Update the JPEG movie file header on the given stream with the given sequence of sound track offsets.
	writeFrame:on:quality:displayFlag: Compress and the given Form on the given stream and answer its offset. If displayFlag is true, show the result of JPEG compression on the display.
	writeFramesFrom:on:quality: Write the frames of the given MPEG movie on the given stream at the given JPEG quality level. Answer a collection of frame offsets. The size of this collection is one larger than the number of frames; it's final entry is the stream position just after the final frame. The byte count for any frame can thus be computed as the difference between two adjacent offsets.
	writeHeaderExtent:frameRate:frameCount:soundtrackCount:on: Write a header on the given stream for a JPEG movie file with the given specifications. Leave the stream positioned at the start of the first movie frame.
	writeSoundTracksFrom:on: Convert and write the sound tracks from the given MPEG file to given stream. Answer a collection of sound track offsets.

	testing	top
	isJPEGMovieFile: Answer true if the file with the given name appears to be a JPEG movie file.