diff options
| -rw-r--r-- | src/demuxers/demux_mpeg.c | 89 |
1 files changed, 66 insertions, 23 deletions
diff --git a/src/demuxers/demux_mpeg.c b/src/demuxers/demux_mpeg.c index 06bf6a364..d846143d5 100644 --- a/src/demuxers/demux_mpeg.c +++ b/src/demuxers/demux_mpeg.c @@ -17,7 +17,7 @@ * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA * - * $Id: demux_mpeg.c,v 1.70 2002/08/06 01:59:22 tmmm Exp $ + * $Id: demux_mpeg.c,v 1.71 2002/08/07 03:13:37 tmmm Exp $ * * demultiplexer for mpeg 1/2 program streams * reads streams of variable blocksizes @@ -106,6 +106,19 @@ typedef struct demux_mpeg_s { #define ATOM_PREAMBLE_SIZE 8 +/* a little something for dealing with RIFF headers */ + +#define FOURCC_TAG(ch0, ch1, ch2, ch3) QT_ATOM(ch0, ch1, ch2, ch3) + +#define RIFF_TAG FOURCC_TAG('R', 'I', 'F', 'F') +#define WAVE_TAG FOURCC_TAG('W', 'A', 'V', 'E') +#define AVI_TAG FOURCC_TAG('A', 'V', 'I', ' ') + +/* arbitrary number of initial file bytes to check for an MPEG marker */ +#define RIFF_CHECK_KILOBYTES 1024 + +#define MPEG_MARKER FOURCC_TAG( 0x00, 0x00, 0x01, 0xBA ) + /* * This function traverses a file and looks for a mdat atom. Upon exit: * *mdat_offset contains the file offset of the beginning of the mdat @@ -925,6 +938,8 @@ static int demux_mpeg_open(demux_plugin_t *this_gen, demux_mpeg_t *this = (demux_mpeg_t *) this_gen; off_t mdat_atom_offset = -1; int64_t mdat_atom_size = -1; + unsigned int fourcc_tag; + int i, j; this->input = input; @@ -939,7 +954,7 @@ static int demux_mpeg_open(demux_plugin_t *this_gen, if(input->get_blocksize(input)) return DEMUX_CANNOT_HANDLE; - if(input->read(input, buf, 6)) { + if(input->read(input, buf, 16) == 16) { if(!buf[0] && !buf[1] && (buf[2] == 0x01)) switch(buf[3]) { @@ -973,34 +988,62 @@ static int demux_mpeg_open(demux_plugin_t *this_gen, /* special case for MPEG streams hidden inside QT files; check * is there is an mdat atom */ find_mdat_atom(input, &mdat_atom_offset, &mdat_atom_size); - if (mdat_atom_offset == -1) - return DEMUX_CANNOT_HANDLE; - - /* seek to the start of the mdat data, which might be in different - * depending on the size type of the atom */ - if (mdat_atom_size == 1) - input->seek(input, mdat_atom_offset + 16, SEEK_SET); - else - input->seek(input, mdat_atom_offset + 8, SEEK_SET); + if (mdat_atom_offset != -1) { + /* seek to the start of the mdat data, which might be in different + * depending on the size type of the atom */ + if (mdat_atom_size == 1) + input->seek(input, mdat_atom_offset + 16, SEEK_SET); + else + input->seek(input, mdat_atom_offset + 8, SEEK_SET); + + /* go through the same MPEG detection song and dance */ + if(input->read(input, buf, 6)) { + if(buf[0] || buf[1] || (buf[2] != 0x01)) + return DEMUX_CANNOT_HANDLE; + + switch(buf[3]) { + + case 0xba: + if((buf[4] & 0xf0) == 0x20) { + uint32_t pckbuf ; + + pckbuf = read_bytes (this, 1); + if ((pckbuf>>4) != 4) { + this->input = input; + return DEMUX_CAN_HANDLE; + } + } + break; + } + } + } - /* go through the same MPEG detection song and dance */ - if(input->read(input, buf, 6)) { - if(buf[0] || buf[1] || (buf[2] != 0x01)) + /* special case for MPEG streams with a RIFF header */ + fourcc_tag = BE_32(&buf[0]); + if (fourcc_tag == RIFF_TAG) { + fourcc_tag = BE_32(&buf[8]); + /* disregard the RIFF file if it is certainly a better known + * format like AVI or WAVE */ + if ((fourcc_tag == WAVE_TAG) || + (fourcc_tag == AVI_TAG)) return DEMUX_CANNOT_HANDLE; - switch(buf[3]) { - - case 0xba: - if((buf[4] & 0xf0) == 0x20) { - uint32_t pckbuf ; - - pckbuf = read_bytes (this, 1); - if ((pckbuf>>4) != 4) { + /* Iterate through first n kilobytes of RIFF file searching for + * MPEG video marker. No, it's not a very efficient approach, but + * if execution has reached this special case, this is currently + * the best chance for detecting the file automatically. Also, + * be extra lazy and do not bother skipping over the data + * header. */ + for (i = 0; i < RIFF_CHECK_KILOBYTES; i++) { + if (input->read(input, buf, 1024) != 1024) + return DEMUX_CANNOT_HANDLE; + + for (j = 0; j < 1024 - 4; j++) { + if (BE_32(&buf[j]) == MPEG_MARKER) { this->input = input; return DEMUX_CAN_HANDLE; } } - break; } } } |