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Originally committed as revision 10363 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
David Conrad 2007-09-05 00:25:16 +00:00
parent a6da1aa057
commit cfde5d18f5
1 changed files with 31 additions and 22 deletions
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53
libavformat/matroskaenc.c
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@ -73,10 +73,12 @@ typedef struct MatroskaMuxContext {
} MatroskaMuxContext;
// 2 bytes * 3 for EBML IDs, 3 1-byte EBML lengths, 8 bytes for 64 bit offset, 4 bytes for target EBML ID
// 2 bytes * 3 for EBML IDs, 3 1-byte EBML lengths, 8 bytes for 64 bit
// offset, 4 bytes for target EBML ID
#define MAX_SEEKENTRY_SIZE 21
// per-cuepoint-track - 3 1-byte EBML IDs, 3 1-byte EBML sizes, 2 8-byte uint max
// per-cuepoint-track - 3 1-byte EBML IDs, 3 1-byte EBML sizes, 2
// 8-byte uint max
#define MAX_CUETRACKPOS_SIZE 22
// per-cuepoint - 2 1-byte EBML IDs, 2 1-byte EBML sizes, 8-byte uint max
@ -188,8 +190,8 @@ static void put_ebml_string(ByteIOContext *pb, unsigned int elementid, const cha
}
/**
* Writes a void element of a given size. Useful for reserving space in the file to be
* written to later.
* Writes a void element of a given size. Useful for reserving space in
* the file to be written to later.
*
* @param size The number of bytes to reserve, which must be at least 2.
*/
@ -201,8 +203,9 @@ static void put_ebml_void(ByteIOContext *pb, uint64_t size)
return;
put_ebml_id(pb, EBML_ID_VOID);
// we need to subtract the length needed to store the size from the size we need to reserve
// so 2 cases, we use 8 bytes to store the size if possible, 1 byte otherwise
// we need to subtract the length needed to store the size from the
// size we need to reserve so 2 cases, we use 8 bytes to store the
// size if possible, 1 byte otherwise
if (size < 10)
put_ebml_size(pb, size-1, 0);
else
@ -236,13 +239,15 @@ static void put_xiph_size(ByteIOContext *pb, int size)
}
/**
* Initialize a mkv_seekhead element to be ready to index level 1 Matroska elements.
* If a maximum number of elements is specified, enough space will be reserved at
* the current file location to write a seek head of that size.
* Initialize a mkv_seekhead element to be ready to index level 1 Matroska
* elements. If a maximum number of elements is specified, enough space
* will be reserved at the current file location to write a seek head of
* that size.
*
* @param segment_offset The absolute offset to the position in the file where the segment begins
* @param numelements the maximum number of elements that will be indexed by this
* seek head, 0 if unlimited.
* @param segment_offset The absolute offset to the position in the file
* where the segment begins
* @param numelements the maximum number of elements that will be indexed
* by this seek head, 0 if unlimited.
*/
static mkv_seekhead * mkv_start_seekhead(ByteIOContext *pb, offset_t segment_offset, int numelements)
{
@ -254,8 +259,9 @@ static mkv_seekhead * mkv_start_seekhead(ByteIOContext *pb, offset_t segment_off
if (numelements > 0) {
new_seekhead->filepos = url_ftell(pb);
// 21 bytes max for a seek entry, 10 bytes max for the SeekHead ID and size,
// and 3 bytes to guarantee that an EBML void element will fit afterwards
// 21 bytes max for a seek entry, 10 bytes max for the SeekHead ID
// and size, and 3 bytes to guarantee that an EBML void element
// will fit afterwards
new_seekhead->reserved_size = numelements * MAX_SEEKENTRY_SIZE + 13;
new_seekhead->max_entries = numelements;
put_ebml_void(pb, new_seekhead->reserved_size);
@ -286,9 +292,10 @@ static int mkv_add_seekhead_entry(mkv_seekhead *seekhead, unsigned int elementid
}
/**
* Write the seek head to the file and free it. If a maximum number of elements was
* specified to mkv_start_seekhead(), the seek head will be written at the location
* reserved for it. Otherwise, it is written at the current location in the file.
* Write the seek head to the file and free it. If a maximum number of
* elements was specified to mkv_start_seekhead(), the seek head will
* be written at the location reserved for it. Otherwise, it is written
* at the current location in the file.
*
* @return the file offset where the seekhead was written
*/
@ -514,7 +521,8 @@ static int mkv_write_tracks(AVFormatContext *s)
else
put_ebml_string(pb, MATROSKA_ID_TRACKLANGUAGE, "und");
// look for a codec id string specific to mkv to use, if none are found, use AVI codes
// look for a codec id string specific to mkv to use,
// if none are found, use AVI codes
for (j = 0; ff_mkv_codec_tags[j].id != CODEC_ID_NONE; j++) {
if (ff_mkv_codec_tags[j].id == codec->codec_id) {
put_ebml_string(pb, MATROSKA_ID_CODECID, ff_mkv_codec_tags[j].str);
@ -627,10 +635,11 @@ static int mkv_write_header(AVFormatContext *s)
mkv->segment = start_ebml_master(pb, MATROSKA_ID_SEGMENT, 0);
mkv->segment_offset = url_ftell(pb);
// we write 2 seek heads - one at the end of the file to point to each cluster, and
// one at the beginning to point to all other level one elements (including the seek
// head at the end of the file), which isn't more than 10 elements if we only write one
// of each other currently defined level 1 element
// we write 2 seek heads - one at the end of the file to point to each
// cluster, and one at the beginning to point to all other level one
// elements (including the seek head at the end of the file), which
// isn't more than 10 elements if we only write one of each other
// currently defined level 1 element
mkv->main_seekhead = mkv_start_seekhead(pb, mkv->segment_offset, 10);
mkv->cluster_seekhead = mkv_start_seekhead(pb, mkv->segment_offset, 0);