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diff --git a/DOCS/edl.rst b/DOCS/edl.rst new file mode 100644 index 0000000000..dcb2f32912 --- /dev/null +++ b/DOCS/edl.rst @@ -0,0 +1,139 @@ +Format of mplayer2 EDL files +============================ + +The first line in the file must be ``mplayer EDL file, version 2``. +The rest of the lines belong to one of these classes: + +1) lines specifying source files +2) empty lines +3) lines specifying timeline segments. + +Lines beginning with ``<`` specify source files. These lines first +contain an identifier used to refer to the source file later, then the +filename separated by whitespace. The identifier must start with a +letter. Filenames that start or end with whitespace or contain +newlines are not supported. + +On other lines ``#`` characters delimit comments. Lines that contain +only whitespace after comments have been removed are ignored. + +Timeline segments must appear in the file in chronological order. Each +segment has the following information associated with it: + +- duration +- output start time +- output end time (= output start time + duration) +- source id (specifies the file the content of the segment comes from) +- source start time (timestamp in the source file) +- source end time (= source start time + duration) + +The output timestamps must form a continuous timeline from 0 to the +end of the last segment, such that each new segment starts from the +time the previous one ends at. Source files and times may change +arbitrarily between segments. + +The general format for lines specifying timeline segments is +[output time info] source_id [source time info] +source_id must be an identifier defined on a ``<`` line. Both the time +info parts consists of zero or more of the following elements: + +1) ``timestamp`` +2) ``-timestamp`` +3) ``+duration`` +4) ``*`` +5) ``-*`` + +, where ``timestamp`` and ``duration`` are decimal numbers (computations +are done with nanosecond precision). Whitespace around ``+`` and ``-`` is +optional. 1) and 2) specify start and end time of the segment on +output or source side. 3) specifies duration; the semantics are the +same whether this appears on output or source side. 4) and 5) are +ignored on the output side (they're always implicitly assumed). On the +source side 4) specifies that the segment starts where the previous +segment *using this source* ended; if there was no previous segment +time 0 is used. 5) specifies that the segment ends where the next +segment using this source starts. + +Redundant information may be omitted. It will be filled in using the +following rules: + +- output start for first segment is 0 +- two of [output start, output end, duration] imply third +- two of [source start, source end, duration] imply third +- output start = output end of previous segment +- output end = output start of next segment +- if ``*``, source start = source end of earlier segment +- if ``-*``, source end = source start of a later segment + +As a special rule, a last zero-duration segment without a source +specification may appear. This will produce no corresponding segment +in the resulting timeline, but can be used as syntax to specify the +end time of the timeline (with effect equal to adding -time on the +previous line). + +Examples:: + + mplayer EDL file, version 2 + < id1 filename + + 0 id1 123 + 100 id1 456 + 200 id1 789 + 300 + +All segments come from the source file ``filename``. First segment +(output time 0-100) comes from time 123-223, second 456-556, third +789-889. + +:: + + mplayer EDL file, version 2 + < f filename + f 60-120 + f 600-660 + f 30- 90 + +Play first seconds 60-120 from the file, then 600-660, then 30-90. + +:: + + mplayer EDL file, version 2 + < id1 filename1 + < id2 filename2 + + +10 id1 * + +10 id2 * + +10 id1 * + +10 id2 * + +10 id1 * + +10 id2 * + +This plays time 0-10 from filename1, then 0-10 from filename1, then +10-20 from filename1, then 10-20 from filename2, then 20-30 from +filename1, then 20-30 from filename2. + +:: + + mplayer EDL file, version 2 + < t1 filename1 + < t2 filename2 + + t1 * +2 # segment 1 + +2 t2 100 # segment 2 + t1 * # segment 3 + t2 *-* # segment 4 + t1 3 -* # segment 5 + +0.111111 t2 102.5 # segment 6 + 7.37 t1 5 +1 # segment 7 + +This rather pathological example illustrates the rules for filling in +implied data. All the values can be determined by recursively applying +the rules given above, and the full end result is this:: + + +2 0-2 t1 0-2 # segment 1 + +2 2-4 t2 100-102 # segment 2 + +0.758889 4-4.758889 t1 2-2.758889 # segment 3 + +0.5 4.4758889-5.258889 t2 102-102.5 # segment 4 + +2 5.258889-7.258889 t1 3-5 # segment 5 + +0.111111 7.258889-7.37 t2 102.5-102.611111 # segment 6 + +1 7.37-8.37 t1 5-6 # segment 7 |