mpv/libmpdemux/demux_edl.c

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EDL: add support for new EDL file format The timeline code previously added to support Matroska ordered chapters allows constructing a playback timeline from segments picked from multiple source files. Add support for a new EDL format to make this machinery available for use with file formats other than Matroska and in a manner easier to use than creating files with ordered chapters. Unlike the old -edl option which specifies an additional file with edits to apply to the video file given as the main argument, the new EDL format is used by giving only the EDL file as the file to play; that file then contains the filename(s) to use as source files where actual video segments come from. Filename paths in the EDL file are ignored. Currently the source files are only searched for in the directory of the EDL file; support for a search path option will likely be added in the future. Format of the 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: ----- begin ----- mplayer EDL file, version 2 < id1 filename 0 id1 123 100 id1 456 200 id1 789 300 ----- end ----- 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. ----- begin ----- mplayer EDL file, version 2 < f filename f 60-120 f 600-660 f 30- 90 ----- end ----- Play first seconds 60-120 from the file, then 600-660, then 30-90. ----- begin ----- mplayer EDL file, version 2 < id1 filename1 < id2 filename2 +10 id1 * +10 id2 * +10 id1 * +10 id2 * +10 id1 * +10 id2 * ----- end ----- 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. ----- begin ----- 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 ----- end ----- 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
2011-02-14 11:05:35 +00:00
/*
* This file is part of MPlayer.
*
* MPlayer is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* MPlayer is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with MPlayer; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include "demuxer.h"
#include "stream/stream.h"
static int try_open_file(struct demuxer *demuxer)
{
struct stream *s = demuxer->stream;
const char header[] = "mplayer EDL file";
const int len = sizeof(header) - 1;
char buf[len];
if (stream_read(s, buf, len) < len)
return 0;
if (strncmp(buf, header, len))
return 0;
stream_seek(s, 0);
demuxer->file_contents = stream_read_complete(s, demuxer, 1000000, 0);
if (demuxer->file_contents.start == NULL)
return 0;
return DEMUXER_TYPE_EDL;
}
static int dummy_fill_buffer(struct demuxer *demuxer, struct demux_stream *ds)
{
return 0;
}
const struct demuxer_desc demuxer_desc_edl = {
.info = "EDL file demuxer",
.name = "edl",
.shortdesc = "EDL",
.author = "Uoti Urpala",
.comment = "",
.type = DEMUXER_TYPE_EDL,
.safe_check = true,
.check_file = try_open_file, // no separate .open
.fill_buffer = dummy_fill_buffer,
};