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mpegtsdemux: Fix multiple-SI detection/parsing

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We had two issues with the previous code:
1) We were badly handling PUSI-flagged packets. We were discarding the
   initial data (if pointer != 0) whereas we should have been accumulating
   it with the previous data (if there was a continuity of course).
   => First series of information loss
2) We were not checking whether there were more sections after the end
   of one (i.e. when the following byte was not a stuff byte).

This fixes those two issues.

Fixes #677443

https://bugzilla.gnome.org/show_bug.cgi?id=677443
This commit is contained in:
Edward Hervey 2013-07-07 08:29:37 +02:00
parent 513417e0ff
commit f58f13e874
3 changed files with 224 additions and 161 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

8
gst/mpegtsdemux/mpegtsbase.c
View file

@ -1110,11 +1110,17 @@ mpegts_base_chain (GstPad * pad, GstObject * parent, GstBuffer * buf)
} else if (packet.payload
&& MPEGTS_BIT_IS_SET (base->known_psi, packet.pid)) {
/* base PSI data */
GList *others, *tmp;
GstMpegTsSection *section;
section = mpegts_packetizer_push_section (packetizer, &packet);
section = mpegts_packetizer_push_section (packetizer, &packet, &others);
if (section)
mpegts_base_handle_psi (base, section);
if (G_UNLIKELY (others)) {
for (tmp = others; tmp; tmp = tmp->next)
mpegts_base_handle_psi (base, (GstMpegTsSection *) tmp->data);
g_list_free (others);
}
/* we need to push section packet downstream */
res = klass->push (base, &packet, section);

373
gst/mpegtsdemux/mpegtspacketizer.c
View file

@ -517,8 +517,9 @@ mpegts_packetizer_parse_section_header (MpegTSPacketizer2 * packetizer,
* pre-parsed header data) */
res =
gst_mpegts_section_new (stream->pid, stream->section_data,
stream->section_allocated);
stream->section_length);
stream->section_data = NULL;
mpegts_packetizer_clear_section (stream);
if (res) {
/* NOTE : Due to the new mpegts-si system, There is a insanely low probability
@ -844,82 +845,32 @@ mpegts_packetizer_clear_packet (MpegTSPacketizer2 * packetizer,
* * With data copied into it (yes, minor overhead)
*
* In all other cases it should just return NULL
*
* If more than one section is available, the 'remaining' field will
* be set to the beginning of a valid GList containing other sections.
* */
GstMpegTsSection *
mpegts_packetizer_push_section (MpegTSPacketizer2 * packetizer,
MpegTSPacketizerPacket * packet)
MpegTSPacketizerPacket * packet, GList ** remaining)
{
GstMpegTsSection *section;
GstMpegTsSection *res = NULL;
MpegTSPacketizerStream *stream;
gboolean long_packet;
guint8 pointer, table_id;
guint8 pointer = 0, table_id;
guint16 subtable_extension = 0;
gsize to_read;
guint section_length;
/* data points to the current read location
* data_start points to the beginning of the data to accumulate */
guint8 *data, *data_start;
guint8 packet_cc;
GList *others = NULL;
guint8 version_number, section_number, last_section_number;
data = packet->data;
packet_cc = FLAGS_CONTINUITY_COUNTER (packet->scram_afc_cc);
GST_MEMDUMP ("section data", packet->data, packet->data_end - packet->data);
/* FIXME: If pointer is different from zero, this means the data should be accumulated
* to the previous section ! */
if (packet->payload_unit_start_indicator) {
pointer = *data++;
/* Sanity check for enough data */
if (data + pointer > packet->data_end) {
GST_DEBUG ("PID 0x%04x PSI section pointer points past the end "
"of the buffer", packet->pid);
goto out;
}
if (G_UNLIKELY (pointer != 0)) {
GST_FIXME ("PID 0x%04x PSI pointer %d != 0. Handle previous data",
packet->pid, pointer);
GST_MEMDUMP ("previous data", data, pointer);
}
data += pointer;
}
/*
* section_syntax_indicator means that the header is of the following format:
* * table_id (8bit)
* * section_syntax_indicator (1bit) == 0
* * reserved/private fields (3bit)
* * section_length (12bit)
* * data (of size section_length)
* * NO CRC !
*/
long_packet = data[1] & 0x80;
/* Fast path for short packets */
if (!long_packet && packet->payload_unit_start_indicator) {
/* We can create the section now (function will check for size) */
GST_DEBUG ("Short packet");
section_length = (GST_READ_UINT16_BE (data + 1) & 0xfff) + 3;
/* Only do fast-path if we have enough byte */
if (section_length < packet->data_end - data) {
res =
gst_mpegts_section_new (packet->pid, g_memdup (data,
section_length), section_length);
if (data[section_length] != 0xff) {
GST_FIXME
("Potentially more data after short section (report in bug #677443)");
GST_MEMDUMP ("Remainder", data + section_length,
packet->data_end - data - section_length);
}
if (res)
res->offset = packet->offset;
/* And exit */
goto out;
}
/* We don't have enough bytes to do short section shortcut */
}
data_start = data;
/* Get our filter */
stream = packetizer->streams[packet->pid];
if (G_UNLIKELY (stream == NULL)) {
@ -932,34 +883,166 @@ mpegts_packetizer_push_section (MpegTSPacketizer2 * packetizer,
packetizer->streams[packet->pid] = stream;
}
/* If not a new section, and we were expecting a new section or
* there is a discontinuity, bail out. */
if (!packet->payload_unit_start_indicator) {
if (stream->continuity_counter == CONTINUITY_UNSET) {
GST_DEBUG ("PID 0x%04x waiting for section start", packet->pid);
goto out;
}
if ((stream->continuity_counter + 1) % 16 != packet_cc) {
GST_WARNING ("PID 0x%04x section discontinuity (%d vs %d)", packet->pid,
stream->continuity_counter, packet_cc);
mpegts_packetizer_clear_section (stream);
goto out;
GST_MEMDUMP ("Full packet data", packet->data,
packet->data_end - packet->data);
/* This function is split into several parts:
*
* Pre checks (packet-wide). Determines where we go next
* accumulate_data: store data and check if section is complete
* section_start: handle beginning of a section, if needed loop back to
* accumulate_data
*
* The trigger that makes the loop stop and return is if:
* 1) We do not have enough data for the current packet
* 2) There is remaining data after a packet which is only made
* of stuffing bytes (0xff).
*
* Pre-loop checks, related to the whole incoming packet:
*
* If there is a CC-discont:
* If it is a PUSI, skip the pointer and handle section_start
* If not a PUSI, reset and return nothing
* If there is not a CC-discont:
* If it is a PUSI
* If pointer, accumulate that data and check for complete section
* (loop)
* If it is not a PUSI
* Accumulate the expected data and check for complete section
* (loop)
*
**/
if (packet->payload_unit_start_indicator) {
pointer = *data++;
/* If the pointer is zero, we're guaranteed to be able to handle it */
if (pointer == 0) {
GST_LOG
("PID 0x%04x PUSI and pointer == 0, skipping straight to section_start parsing",
packet->pid);
goto section_start;
}
}
if (packet->payload_unit_start_indicator) {
guint8 version_number, section_number, last_section_number;
if (stream->continuity_counter == CONTINUITY_UNSET ||
(stream->continuity_counter + 1) % 16 != packet_cc) {
if (stream->continuity_counter != CONTINUITY_UNSET)
GST_WARNING ("PID 0x%04x section discontinuity (%d vs %d)", packet->pid,
stream->continuity_counter, packet_cc);
mpegts_packetizer_clear_section (stream);
/* If not a PUSI, not much we can do */
if (!packet->payload_unit_start_indicator) {
GST_LOG ("PID 0x%04x continuity discont/unset and not PUSI, bailing out",
packet->pid);
goto out;
}
/* If PUSI, skip pointer data and carry on to section start */
data += pointer;
pointer = 0;
GST_LOG ("discont, but PUSI, skipped %d bytes and doing section start",
pointer);
goto section_start;
}
/* Beginning of a new section, do as much pre-parsing as possible */
/* table_id : 8 bit */
table_id = *data++;
GST_LOG ("Accumulating data from beginning of packet");
/* section_syntax_indicator : 1 bit
* other_fields (reserved) : 3 bit
* section_length : 12 bit */
section_length = (GST_READ_UINT16_BE (data) & 0x0FFF) + 3;
data += 2;
data_start = data;
accumulate_data:
/* If not the beginning of a new section, accumulate what we have */
stream->continuity_counter = packet_cc;
to_read = MIN (stream->section_length - stream->section_offset,
packet->data_end - data_start);
memcpy (stream->section_data + stream->section_offset, data_start, to_read);
stream->section_offset += to_read;
/* Point data to after the data we accumulated */
data = data_start + to_read;
GST_DEBUG ("Appending data (need %d, have %d)", stream->section_length,
stream->section_offset);
/* Check if we have enough */
if (stream->section_offset < stream->section_length) {
GST_DEBUG ("PID 0x%04x, section not complete (Got %d, need %d)",
stream->pid, stream->section_offset, stream->section_length);
goto out;
}
/* Small sanity check. We should have collected *exactly* the right amount */
if (G_UNLIKELY (stream->section_offset != stream->section_length))
GST_WARNING ("PID 0x%04x Accumulated too much data (%d vs %d) !",
stream->pid, stream->section_offset, stream->section_length);
GST_DEBUG ("PID 0x%04x Section complete", stream->pid);
if ((section = mpegts_packetizer_parse_section_header (packetizer, stream))) {
if (res)
others = g_list_append (others, section);
else
res = section;
}
if (data == packet->data_end || *data == 0xff) {
/* flush stuffing bytes and leave */
mpegts_packetizer_clear_section (stream);
goto out;
}
/* We have more data to process ... */
GST_DEBUG ("PID 0x%04x, More section present in packet (remaining bytes:%"
G_GSIZE_FORMAT ")", stream->pid, packet->data_end - data);
section_start:
GST_MEMDUMP ("section_start", data, packet->data_end - data);
data_start = data;
/* Beginning of a new section */
/*
* section_syntax_indicator means that the header is of the following format:
* * table_id (8bit)
* * section_syntax_indicator (1bit) == 0
* * reserved/private fields (3bit)
* * section_length (12bit)
* * data (of size section_length)
* * NO CRC !
*/
long_packet = data[1] & 0x80;
/* Fast path for short packets */
if (!long_packet) {
/* We can create the section now (function will check for size) */
GST_DEBUG ("Short packet");
section_length = (GST_READ_UINT16_BE (data + 1) & 0xfff) + 3;
/* Only do fast-path if we have enough byte */
if (section_length < packet->data_end - data) {
if ((section =
gst_mpegts_section_new (packet->pid, g_memdup (data,
section_length), section_length))) {
GST_DEBUG ("PID 0x%04x Short section complete !", packet->pid);
section->offset = packet->offset;
if (res)
others = g_list_append (others, section);
else
res = section;
}
/* Advance reader and potentially read another section */
data += section_length;
if (data < packet->data_end && *data != 0xff)
goto section_start;
/* If not, exit */
goto out;
}
/* We don't have enough bytes to do short section shortcut */
}
/* Beginning of a new section, do as much pre-parsing as possible */
/* table_id : 8 bit */
table_id = *data++;
/* section_syntax_indicator : 1 bit
* other_fields (reserved) : 3 bit
* section_length : 12 bit */
section_length = (GST_READ_UINT16_BE (data) & 0x0FFF) + 3;
data += 2;
if (long_packet) {
/* subtable_extension (always present, we are in a long section) */
/* subtable extension : 16 bit */
subtable_extension = GST_READ_UINT16_BE (data);
@ -981,89 +1064,65 @@ mpegts_packetizer_push_section (MpegTSPacketizer2 * packetizer,
section_number = *data++;
/* last_section_number : 8 bit */
last_section_number = *data++;
} else {
subtable_extension = 0;
version_number = 0;
section_number = 0;
last_section_number = 0;
}
GST_DEBUG
("PID 0x%04x length:%d table_id:0x%02x subtable_extension:0x%04x version_number:%d section_number:%d(last:%d)",
packet->pid, section_length, table_id, subtable_extension, version_number,
section_number, last_section_number);
to_read = MIN (section_length, packet->data_end - data_start);
/* Check as early as possible whether we already saw this section
* i.e. that we saw a subtable with:
* * same subtable_extension (might be zero)
* * same version_number
* * same last_section_number
* * same section_number was seen
*/
if (seen_section_before (stream, table_id, subtable_extension,
version_number, section_number, last_section_number)) {
GST_DEBUG
("PID 0x%04x table_id:0x%02x subtable_extension:0x%04x version_number:%d section_number:%d(last:%d)",
("PID 0x%04x Already processed table_id:0x%02x subtable_extension:0x%04x, version_number:%d, section_number:%d",
packet->pid, table_id, subtable_extension, version_number,
section_number, last_section_number);
/* Check as early as possible whether we already saw this section
* i.e. that we saw a subtable with:
* * same subtable_extension (might be zero)
* * same version_number
* * same last_section_number
* * same section_number was seen
*/
if (seen_section_before (stream, table_id, subtable_extension,
version_number, section_number, last_section_number)) {
GST_DEBUG
("PID 0x%04x Already processed table_id:0x%02x subtable_extension:0x%04x, version_number:%d, section_number:%d",
packet->pid, table_id, subtable_extension, version_number,
section_number);
section_number);
/* skip data and see if we have more sections after */
data = data_start + to_read;
if (data == packet->data_end || *data == 0xff)
goto out;
}
if (G_UNLIKELY (section_number > last_section_number)) {
GST_WARNING
("PID 0x%04x corrupted packet (section_number:%d > last_section_number:%d)",
packet->pid, section_number, last_section_number);
goto out;
}
stream->continuity_counter = packet_cc;
/* Copy over already parsed values */
stream->table_id = table_id;
stream->section_length = section_length;
stream->version_number = version_number;
stream->subtable_extension = subtable_extension;
stream->section_number = section_number;
stream->last_section_number = last_section_number;
/* Create enough room to store chunks of sections, including FF padding */
stream->section_allocated = stream->section_length + 188;
stream->section_data = g_malloc (stream->section_allocated);
memcpy (stream->section_data, data_start, packet->data_end - data_start);
stream->section_offset = packet->data_end - data_start;
stream->offset = packet->offset;
} else {
/* valid continuation of an existing section */
stream->continuity_counter = packet_cc;
memcpy (stream->section_data + stream->section_offset, data_start,
packet->data_end - data_start);
stream->section_offset += packet->data_end - data_start;
GST_DEBUG ("Appending data (need %d, have %d)", stream->section_length,
stream->section_offset);
goto section_start;
}
if (G_UNLIKELY (section_number > last_section_number)) {
GST_WARNING
("PID 0x%04x corrupted packet (section_number:%d > last_section_number:%d)",
packet->pid, section_number, last_section_number);
goto out;
}
/* we pushed some data in the section adapter, see if the section is
* complete now */
/* >= as sections can be padded and padding is not included in
* section_length */
if (stream->section_offset >= stream->section_length) {
GST_DEBUG ("PID 0x%04x Section complete (Got %d, need %d)",
stream->pid, stream->section_offset, stream->section_length);
/* Remainder of section data should be padding (0xff) */
/* Adding a warning so people can report it in the bug reported regarding
* multiple sections after another (still not seen any samples in the wild) */
if (stream->section_offset > stream->section_length &&
stream->section_data[stream->section_length] != 0xff) {
GST_FIXME ("Potentially more data after section (report in bug #677443)");
GST_MEMDUMP ("Remainder", stream->section_data + stream->section_length,
stream->section_offset - stream->section_length);
}
res = mpegts_packetizer_parse_section_header (packetizer, stream);
/* flush stuffing bytes */
mpegts_packetizer_clear_section (stream);
} else {
GST_DEBUG ("PID 0x%04x, section not complete (Got %d, need %d)",
stream->pid, stream->section_offset, stream->section_length);
}
/* Copy over already parsed values */
stream->table_id = table_id;
stream->section_length = section_length;
stream->version_number = version_number;
stream->subtable_extension = subtable_extension;
stream->section_number = section_number;
stream->last_section_number = last_section_number;
stream->offset = packet->offset;
/* Create enough room to store chunks of sections */
stream->section_data = g_malloc (stream->section_length);
stream->section_offset = 0;
/* Finally, accumulate and check if we parsed enough */
goto accumulate_data;
out:
packet->data = data;
*remaining = others;
GST_DEBUG ("result: %p", res);

4
gst/mpegtsdemux/mpegtspacketizer.h
View file

@ -68,8 +68,6 @@ typedef struct
/* Section data (always newly allocated) */
guint8 *section_data;
/* Allocated length of section_data */
guint section_allocated;
/* Current offset in section_data */
guint16 section_offset;
@ -182,7 +180,7 @@ G_GNUC_INTERNAL void mpegts_packetizer_remove_stream(MpegTSPacketizer2 *packetiz
gint16 pid);
G_GNUC_INTERNAL GstMpegTsSection *mpegts_packetizer_push_section (MpegTSPacketizer2 *packetzer,
MpegTSPacketizerPacket *packet);
MpegTSPacketizerPacket *packet, GList **remaining);
/* Only valid if calculate_offset is TRUE */
G_GNUC_INTERNAL guint mpegts_packetizer_get_seen_pcr (MpegTSPacketizer2 *packetizer);