From 6b2e142ccbc089cb469ba1693e0ccfd3e17f2c67 Mon Sep 17 00:00:00 2001 From: "Ronald S. Bultje" Date: Fri, 23 Jan 2004 16:55:21 +0000 Subject: [PATCH] gst/typefind/gsttypefindfunctions.c: Fix MPEG-1 stream typefinding. Original commit message from CVS: 2004-01-23 Ronald Bultje * gst/typefind/gsttypefindfunctions.c: (mpeg1_parse_header), (mpeg1_sys_type_find): Fix MPEG-1 stream typefinding. --- ChangeLog | 6 ++ gst/typefind/gsttypefindfunctions.c | 124 +++++++++++++++++++++--------------- 2 files changed, 78 insertions(+), 52 deletions(-) diff --git a/ChangeLog b/ChangeLog index 04b65a9..210572e 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,11 @@ 2004-01-23 Ronald Bultje + * gst/typefind/gsttypefindfunctions.c: (mpeg1_parse_header), + (mpeg1_sys_type_find): + Fix MPEG-1 stream typefinding. + +2004-01-23 Ronald Bultje + * gst/typefind/gsttypefindfunctions.c: (mpeg2_sys_type_find): Fix typefinding for MPEG-1 system streams, similar to MPEG-2. diff --git a/gst/typefind/gsttypefindfunctions.c b/gst/typefind/gsttypefindfunctions.c index 8b1db63..6183e6b 100644 --- a/gst/typefind/gsttypefindfunctions.c +++ b/gst/typefind/gsttypefindfunctions.c @@ -449,74 +449,94 @@ mpeg2_sys_type_find (GstTypeFind *tf, gpointer unused) static guint mpeg1_parse_header (GstTypeFind *tf, guint64 offset) { - guint8 *data = gst_type_find_peek (tf, offset, 18); + guint8 *data = gst_type_find_peek (tf, offset, 4); guint size; if (!data) { - GST_LOG ("couldn't get 18 bytes to parse MPEG header"); + GST_LOG ("couldn't get MPEG header bytes"); return 1; } - - /* check header */ - if (!IS_MPEG_HEADER (data)) { - GST_LOG ("This isn't an MPEG header"); - return 0; - } - data += 4; - /* check marker bits */ - if ((*data & 0xF1) != 0x21) { - GST_LOG ("marker bits in byte 4 don't match"); - return 0; - } - data += 2; - if ((*data & 0x01) != 0x01) { - GST_LOG ("marker bits in byte 6 don't match"); - return 0; - } - data += 2; - if ((*data & 0x01) != 0x01) { - GST_LOG ("marker bits in byte 8 don't match"); + if (data[0] != 0 || data[1] != 0 || data[2] != 1) { return 0; } - data ++; - if ((*data & 0x80) != 0x80) { - GST_LOG ("marker bits in byte 9 don't match"); - return 0; - } - data += 2; - if ((*data & 0x01) != 0x01) { - GST_LOG ("marker bits in byte 11 don't match"); - return 0; - } - data++; - - if (!IS_MPEG_PACKET_HEADER (data) && - !IS_MPEG_SYSTEM_HEADER (data)) { - GST_LOG ("MPEG packet header doesn't match: %8.8X", GUINT32_FROM_BE (*((guint32 *) data))); - return 0; + offset += 4; + + switch (data[3]) { + case 0xBA: /* pack header */ + data = gst_type_find_peek (tf, offset, 8); + if (!data) { + GST_LOG ("couldn't get MPEG pack header bytes"); + return 1; + } + size = 12; + /* check marker bits */ + if ((data[0] & 0xF1) != 0x21 || + (data[2] & 0x01) != 0x01 || + (data[4] & 0x01) != 0x01 || + (data[5] & 0x80) != 0x80 || + (data[7] & 0x01) != 0x01) + return 0; + break; + + case 0xB9: /* ISO end code */ + size = 4; + break; + + case 0xBB: /* system header */ + data = gst_type_find_peek (tf, offset, 2); + if (!data) { + GST_LOG ("couldn't get MPEG pack header bytes"); + return 1; + } + size = GUINT16_FROM_BE (* (guint16 *) data) + 6; + offset += 2; + data = gst_type_find_peek (tf, offset, size - 6); + if (!data) { + GST_LOG ("couldn't get MPEG pack header bytes"); + return 1; + } + /* check marker bits */ + if ((data[0] & 0x80) != 0x80 || + (data[2] & 0x01) != 0x01 || + (data[4] & 0x20) != 0x20) + return 0; + /* check stream marker bits */ + for (offset = 6; offset < (size - 6); offset += 3) { + if (data[offset] <= 0xBB || + (data[offset + 1] & 0xC0) != 0xC0) + return 0; + } + break; + + default: + if (data[3] < 0xB9) + return 0; + data = gst_type_find_peek (tf, offset, 2); + if (!data) { + GST_LOG ("couldn't get MPEG pack header bytes"); + return 1; + } + size = GUINT16_FROM_BE (* (guint16 *) data) + 6; + /* FIXME: we could check PTS/DTS marker bits here... (bit overkill) */ + break; } - - data += 4; - - size = GUINT16_FROM_BE (*((guint16 *) data)) + 18; - GST_DEBUG ("found mpeg1 packet at offset %"G_GUINT64_FORMAT" with size %u", offset, size); return size; } /* calculation of possibility to identify random data as mpeg systemstream: - * bits that must match in header detection: 65 - * chance that random data is identifed: 1/2^65 + * bits that must match in header detection: 32 (or more) + * chance that random data is identifed: 1/2^32 * chance that GST_MPEG_TYPEFIND_TRY_HEADERS headers are identified: - * 1/2^(65*GST_MPEG_TYPEFIND_TRY_HEADERS) + * 1/2^(32*GST_MPEG_TYPEFIND_TRY_HEADERS) * chance that this happens in GST_MPEG_TYPEFIND_TRY_SYNC bytes: - * 1-(1-1/2^(65*GST_MPEG_TYPEFIND_TRY_HEADERS))^GST_MPEG_TYPEFIND_TRY_SYNC + * 1-(1+1/2^(32*GST_MPEG_TYPEFIND_TRY_HEADERS)^GST_MPEG_TYPEFIND_TRY_SYNC) * for current values: - * 1-(1-1/2^(65*2)^50000 - * = 3.6734..*10^-35 + * 1-(1+1/2^(32*4)^101024) + * = */ -#define GST_MPEG_TYPEFIND_TRY_HEADERS 2 -#define GST_MPEG_TYPEFIND_TRY_SYNC (GST_TYPE_FIND_MAXIMUM * 500) /* 50kB */ +#define GST_MPEG_TYPEFIND_TRY_HEADERS 4 +#define GST_MPEG_TYPEFIND_TRY_SYNC (100 * 1024) /* 100kB */ #define GST_MPEG_TYPEFIND_SYNC_SIZE 2048 static void mpeg1_sys_type_find (GstTypeFind *tf, gpointer unused) @@ -538,7 +558,7 @@ mpeg1_sys_type_find (GstTypeFind *tf, gpointer unused) guint found = 0; guint packet_size = 0; guint64 offset = skipped; - + while (found < GST_MPEG_TYPEFIND_TRY_HEADERS) { packet_size = mpeg1_parse_header (tf, offset); if (packet_size <= 1) -- 2.7.4