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gstreamer/gst/mpegvideoparse/mpegvideoparse.c
Mark Nauwelaerts c63be1402a mpegvideoparse: prevent some fall-through cases
2012-01-23 14:22:17 +01:00

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/* GStreamer
* Copyright (C) <1999> Erik Walthinsen <omega@cse.ogi.edu>
* Copyright (C) <2007> Jan Schmidt <thaytan@mad.scientist.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <string.h>
#include "mpegvideoparse.h"
/* FIXME: there are still some things to do in this element.
* + Handle Sequence Display Extension to output the display size
* rather than the encoded size.
* + Do all the other stuff (documentation, tests) to get it into
* ugly or good.
* + low priority:
* - handle seeking in raw elementary streams
* - calculate timestamps for all un-timestamped frames, taking into
* account frame re-ordering. Doing this probably requires introducing
* an extra end-to-end delay however, so might not be really desirable.
* - Collect a list of regions and the sequence headers that apply
* to each region so that we properly handle SEQUENCE_END followed
* by a new sequence. At the moment, the caps will change if the
* sequence changes, but if we then seek to a different spot it might
* be wrong. Fortunately almost every stream only has 1 sequence.
*/
GST_DEBUG_CATEGORY (mpv_parse_debug);
#define GST_CAT_DEFAULT mpv_parse_debug
static GstStaticPadTemplate src_template =
GST_STATIC_PAD_TEMPLATE ("src", GST_PAD_SRC,
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("video/mpeg, "
"mpegversion = (int) [ 1, 2 ], "
"parsed = (boolean) true, "
"systemstream = (boolean) false, "
"width = (int) [ 16, 4096 ], "
"height = (int) [ 16, 4096 ], "
"pixel-aspect-ratio = (fraction) [ 0/1, MAX ], "
"framerate = (fraction) [ 0/1, MAX ]")
);
static GstStaticPadTemplate sink_template = GST_STATIC_PAD_TEMPLATE ("sink",
GST_PAD_SINK,
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("video/mpeg, "
"mpegversion = (int) [ 1, 2 ], "
"parsed = (boolean) false, " "systemstream = (boolean) false")
);
/* MpegVideoParse signals and args */
enum
{
/* FILL ME */
LAST_SIGNAL
};
enum
{
ARG_0
/* FILL ME */
};
static void gst_mpegvideoparse_class_init (MpegVideoParseClass * klass);
static void gst_mpegvideoparse_base_init (MpegVideoParseClass * klass);
static void gst_mpegvideoparse_init (MpegVideoParse * mpegvideoparse);
static void gst_mpegvideoparse_dispose (GObject * object);
static GstFlowReturn gst_mpegvideoparse_chain (GstPad * pad, GstBuffer * buf);
static gboolean mpv_parse_sink_event (GstPad * pad, GstEvent * event);
static void gst_mpegvideoparse_flush (MpegVideoParse * mpegvideoparse);
static GstStateChangeReturn
gst_mpegvideoparse_change_state (GstElement * element,
GstStateChange transition);
static void mpv_send_pending_segs (MpegVideoParse * mpegvideoparse);
static void mpv_clear_pending_segs (MpegVideoParse * mpegvideoparse);
static GstElementClass *parent_class = NULL;
/*static guint gst_mpegvideoparse_signals[LAST_SIGNAL] = { 0 }; */
GType
mpegvideoparse_get_type (void)
{
static GType mpegvideoparse_type = 0;
if (!mpegvideoparse_type) {
static const GTypeInfo mpegvideoparse_info = {
sizeof (MpegVideoParseClass),
(GBaseInitFunc) gst_mpegvideoparse_base_init,
NULL,
(GClassInitFunc) gst_mpegvideoparse_class_init,
NULL,
NULL,
sizeof (MpegVideoParse),
0,
(GInstanceInitFunc) gst_mpegvideoparse_init,
};
mpegvideoparse_type =
g_type_register_static (GST_TYPE_ELEMENT, "MpegVideoParse",
&mpegvideoparse_info, 0);
}
return mpegvideoparse_type;
}
static void
gst_mpegvideoparse_base_init (MpegVideoParseClass * klass)
{
GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
gst_element_class_add_static_pad_template (element_class, &src_template);
gst_element_class_add_static_pad_template (element_class,
&sink_template);
gst_element_class_set_details_simple (element_class,
"MPEG video elementary stream parser",
"Codec/Parser/Video",
"Parses and frames MPEG-1 and MPEG-2 elementary video streams",
"Wim Taymans <wim.taymans@chello.be>, "
"Jan Schmidt <thaytan@mad.scientist.com>");
}
static void
gst_mpegvideoparse_class_init (MpegVideoParseClass * klass)
{
GObjectClass *gobject_class;
GstElementClass *gstelement_class;
gstelement_class = (GstElementClass *) klass;
gobject_class = G_OBJECT_CLASS (klass);
parent_class = g_type_class_peek_parent (klass);
gobject_class->dispose = (GObjectFinalizeFunc) (gst_mpegvideoparse_dispose);
gstelement_class->change_state = gst_mpegvideoparse_change_state;
}
static void
mpv_parse_reset (MpegVideoParse * mpegvideoparse)
{
mpegvideoparse->seq_hdr.mpeg_version = 0;
mpegvideoparse->seq_hdr.width = mpegvideoparse->seq_hdr.height = -1;
mpegvideoparse->seq_hdr.fps_n = mpegvideoparse->seq_hdr.par_w = 0;
mpegvideoparse->seq_hdr.fps_d = mpegvideoparse->seq_hdr.par_h = 1;
mpv_clear_pending_segs (mpegvideoparse);
}
static void
mpv_send_pending_segs (MpegVideoParse * mpegvideoparse)
{
while (mpegvideoparse->pending_segs) {
GstEvent *ev = mpegvideoparse->pending_segs->data;
gst_pad_push_event (mpegvideoparse->srcpad, ev);
mpegvideoparse->pending_segs =
g_list_delete_link (mpegvideoparse->pending_segs,
mpegvideoparse->pending_segs);
}
mpegvideoparse->pending_segs = NULL;
}
static void
mpv_clear_pending_segs (MpegVideoParse * mpegvideoparse)
{
while (mpegvideoparse->pending_segs) {
GstEvent *ev = mpegvideoparse->pending_segs->data;
gst_event_unref (ev);
mpegvideoparse->pending_segs =
g_list_delete_link (mpegvideoparse->pending_segs,
mpegvideoparse->pending_segs);
}
}
static void
gst_mpegvideoparse_init (MpegVideoParse * mpegvideoparse)
{
mpegvideoparse->sinkpad =
gst_pad_new_from_static_template (&sink_template, "sink");
gst_pad_set_chain_function (mpegvideoparse->sinkpad,
gst_mpegvideoparse_chain);
gst_pad_set_event_function (mpegvideoparse->sinkpad, mpv_parse_sink_event);
gst_element_add_pad (GST_ELEMENT (mpegvideoparse), mpegvideoparse->sinkpad);
mpegvideoparse->srcpad =
gst_pad_new_from_static_template (&src_template, "src");
gst_pad_use_fixed_caps (mpegvideoparse->srcpad);
gst_element_add_pad (GST_ELEMENT (mpegvideoparse), mpegvideoparse->srcpad);
mpeg_packetiser_init (&mpegvideoparse->packer);
mpv_parse_reset (mpegvideoparse);
}
void
gst_mpegvideoparse_dispose (GObject * object)
{
MpegVideoParse *mpegvideoparse = GST_MPEGVIDEOPARSE (object);
mpeg_packetiser_free (&mpegvideoparse->packer);
gst_buffer_replace (&mpegvideoparse->seq_hdr_buf, NULL);
G_OBJECT_CLASS (parent_class)->dispose (object);
}
static gboolean
mpegvideoparse_handle_sequence (MpegVideoParse * mpegvideoparse,
GstBuffer * buf)
{
MPEGSeqHdr new_hdr;
guint8 *cur, *end;
cur = GST_BUFFER_DATA (buf);
end = GST_BUFFER_DATA (buf) + GST_BUFFER_SIZE (buf);
memset (&new_hdr, 0, sizeof (MPEGSeqHdr));
if (G_UNLIKELY (!mpeg_util_parse_sequence_hdr (&new_hdr, cur, end)))
return FALSE;
if (new_hdr.width < 16 || new_hdr.width > 4096 ||
new_hdr.height < 16 || new_hdr.height > 4096) {
GST_WARNING_OBJECT (mpegvideoparse, "Width/height out of valid range "
"[16, 4096]");
return FALSE;
}
if (memcmp (&mpegvideoparse->seq_hdr, &new_hdr, sizeof (MPEGSeqHdr)) != 0) {
GstCaps *caps;
GstBuffer *seq_buf;
/*
* Profile indication - 1 => High, 2 => Spatially Scalable,
* 3 => SNR Scalable, 4 => Main, 5 => Simple
* 4:2:2 and Multi-view have profile = 0, with the escape bit set to 1
*/
const gchar *profiles[] = { "high", "spatial", "snr", "main", "simple" };
/*
* Level indication - 4 => High, 6 => High-1440, 8 => Main, 10 => Low,
* except in the case of profile = 0
*/
const gchar *levels[] = { "high", "high-1440", "main", "low" };
/* Store the entire sequence header + sequence header extension
for output as codec_data */
seq_buf = gst_buffer_copy (buf);
gst_buffer_replace (&mpegvideoparse->seq_hdr_buf, seq_buf);
gst_buffer_unref (seq_buf);
caps = gst_caps_new_simple ("video/mpeg",
"systemstream", G_TYPE_BOOLEAN, FALSE,
"parsed", G_TYPE_BOOLEAN, TRUE,
"mpegversion", G_TYPE_INT, new_hdr.mpeg_version,
"width", G_TYPE_INT, new_hdr.width,
"height", G_TYPE_INT, new_hdr.height,
"framerate", GST_TYPE_FRACTION, new_hdr.fps_n, new_hdr.fps_d,
"pixel-aspect-ratio", GST_TYPE_FRACTION, new_hdr.par_w, new_hdr.par_h,
"interlaced", G_TYPE_BOOLEAN, !new_hdr.progressive,
"codec_data", GST_TYPE_BUFFER, seq_buf, NULL);
if (new_hdr.mpeg_version == 2) {
const gchar *profile = NULL, *level = NULL;
if (new_hdr.profile > 0 && new_hdr.profile < 6)
profile = profiles[new_hdr.profile - 1];
if ((new_hdr.level > 3) && (new_hdr.level < 11) &&
(new_hdr.level % 2 == 0))
level = levels[(new_hdr.level >> 1) - 1];
if (new_hdr.profile == 8) {
/* Non-hierarchical profile */
switch (new_hdr.level) {
case 2:
level = levels[0];
break;
case 5:
level = levels[2];
profile = "4:2:2";
break;
case 10:
level = levels[0];
break;
case 11:
level = levels[1];
break;
case 13:
level = levels[2];
break;
case 14:
level = levels[3];
profile = "multiview";
break;
default:
break;
}
}
if (profile)
gst_caps_set_simple (caps, "profile", G_TYPE_STRING, profile, NULL);
else
GST_DEBUG ("Invalid profile - %u", new_hdr.profile);
if (level)
gst_caps_set_simple (caps, "level", G_TYPE_STRING, level, NULL);
else
GST_DEBUG ("Invalid level - %u", new_hdr.level);
}
GST_DEBUG ("New mpegvideoparse caps: %" GST_PTR_FORMAT, caps);
if (!gst_pad_set_caps (mpegvideoparse->srcpad, caps)) {
gst_caps_unref (caps);
return FALSE;
}
gst_caps_unref (caps);
if (new_hdr.bitrate > 0) {
GstTagList *taglist;
taglist = gst_tag_list_new_full (GST_TAG_BITRATE, new_hdr.bitrate, NULL);
gst_element_found_tags_for_pad (GST_ELEMENT_CAST (mpegvideoparse),
mpegvideoparse->srcpad, taglist);
}
/* And update the new_hdr into our stored version */
mpegvideoparse->seq_hdr = new_hdr;
}
return TRUE;
}
#ifndef GST_DISABLE_GST_DEBUG
static const gchar *
picture_start_code_name (guint8 psc)
{
guint i;
const struct
{
guint8 psc;
const gchar *name;
} psc_names[] = {
{
0x00, "Picture Start"}, {
0xb0, "Reserved"}, {
0xb1, "Reserved"}, {
0xb2, "User Data Start"}, {
0xb3, "Sequence Header Start"}, {
0xb4, "Sequence Error"}, {
0xb5, "Extnsion Start"}, {
0xb6, "Reserved"}, {
0xb7, "Sequence End"}, {
0xb8, "Group Start"}, {
0xb9, "Program End"}
};
if (psc < 0xB0 && psc > 0)
return "Slice Start";
for (i = 0; i < G_N_ELEMENTS (psc_names); i++)
if (psc_names[i].psc == psc)
return psc_names[i].name;
return "UNKNOWN";
};
static const gchar *
picture_type_name (guint8 pct)
{
guint i;
const struct
{
guint8 pct;
const gchar *name;
} pct_names[] = {
{
0, "Forbidden"}, {
1, "I Frame"}, {
2, "P Frame"}, {
3, "B Frame"}, {
4, "DC Intra Coded (Shall Not Be Used!)"}
};
for (i = 0; i < G_N_ELEMENTS (pct_names); i++)
if (pct_names[i].pct == pct)
return pct_names[i].name;
return "Reserved/Unknown";
}
#endif /* GST_DISABLE_GST_DEBUG */
static gboolean
mpegvideoparse_handle_picture (MpegVideoParse * mpegvideoparse, GstBuffer * buf)
{
guint8 *cur, *end;
guint32 sync_word = 0xffffffff;
cur = GST_BUFFER_DATA (buf);
end = GST_BUFFER_DATA (buf) + GST_BUFFER_SIZE (buf);
cur = mpeg_util_find_start_code (&sync_word, cur, end);
while (cur != NULL) {
if (cur[0] == 0 || cur[0] > 0xaf)
GST_LOG_OBJECT (mpegvideoparse, "Picture Start Code : %s",
picture_start_code_name (cur[0]));
/* Cur points at the last byte of the start code */
if (cur[0] == MPEG_PACKET_PICTURE) {
guint8 *pic_data = cur - 3;
MPEGPictureHdr hdr;
/* pic_data points to the first byte of the sync word now */
if (!mpeg_util_parse_picture_hdr (&hdr, pic_data, end))
return FALSE;
if (hdr.pic_type != MPEG_PICTURE_TYPE_I)
GST_BUFFER_FLAG_SET (buf, GST_BUFFER_FLAG_DELTA_UNIT);
GST_LOG_OBJECT (mpegvideoparse, "Picture type is %s",
picture_type_name (hdr.pic_type));
/* FIXME: Can use the picture type and number of fields to track a
* timestamp */
break;
}
cur = mpeg_util_find_start_code (&sync_word, cur, end);
}
return TRUE;
}
#if 0
static guint64
gst_mpegvideoparse_time_code (guchar * gop, MPEGSeqHdr * seq_hdr)
{
guint32 data = GST_READ_UINT32_BE (gop);
guint64 seconds;
guint8 frames;
seconds = ((data & 0xfc000000) >> 26) * 3600; /* hours */
seconds += ((data & 0x03f00000) >> 20) * 60; /* minutes */
seconds += (data & 0x0007e000) >> 13; /* seconds */
frames = (data & 0x00001f80) >> 7;
return seconds * GST_SECOND + gst_util_uint64_scale_int (frames * GST_SECOND,
seq_hdr->fps_d, seq_hdr->fps_n);
}
#endif
static void
gst_mpegvideoparse_flush (MpegVideoParse * mpegvideoparse)
{
GST_DEBUG_OBJECT (mpegvideoparse, "mpegvideoparse: flushing");
mpegvideoparse->next_offset = GST_BUFFER_OFFSET_NONE;
g_list_foreach (mpegvideoparse->gather, (GFunc) gst_mini_object_unref, NULL);
g_list_free (mpegvideoparse->gather);
mpegvideoparse->gather = NULL;
g_list_foreach (mpegvideoparse->decode, (GFunc) gst_mini_object_unref, NULL);
g_list_free (mpegvideoparse->decode);
mpegvideoparse->decode = NULL;
mpeg_packetiser_flush (&mpegvideoparse->packer);
mpv_clear_pending_segs (mpegvideoparse);
}
static GstFlowReturn
mpegvideoparse_drain_avail (MpegVideoParse * mpegvideoparse)
{
MPEGBlockInfo *cur;
GstBuffer *buf = NULL;
GstFlowReturn res = GST_FLOW_OK;
cur = mpeg_packetiser_get_block (&mpegvideoparse->packer, &buf);
while ((cur != NULL) && (res == GST_FLOW_OK)) {
/* Handle the block */
GST_LOG_OBJECT (mpegvideoparse,
"Have block of size %u with pack_type %s and flags 0x%02x",
cur->length, picture_start_code_name (cur->first_pack_type),
cur->flags);
if ((cur->flags & MPEG_BLOCK_FLAG_SEQUENCE) && buf != NULL) {
/* Found a sequence header */
if (!mpegvideoparse_handle_sequence (mpegvideoparse, buf)) {
GST_DEBUG_OBJECT (mpegvideoparse,
"Invalid sequence header. Dropping buffer.");
gst_buffer_unref (buf);
buf = NULL;
}
} else if (mpegvideoparse->seq_hdr.mpeg_version == 0 && buf) {
/* Don't start pushing out buffers until we've seen a sequence header */
GST_DEBUG_OBJECT (mpegvideoparse,
"No sequence header yet. Dropping buffer of %u bytes",
GST_BUFFER_SIZE (buf));
gst_buffer_unref (buf);
buf = NULL;
}
if (buf != NULL) {
/* If outputting a PICTURE packet, we can calculate the duration
and possibly the timestamp */
if (cur->flags & MPEG_BLOCK_FLAG_PICTURE) {
if (!mpegvideoparse_handle_picture (mpegvideoparse, buf)) {
/* Corrupted picture. Drop it. */
GST_DEBUG_OBJECT (mpegvideoparse,
"Corrupted picture header. Dropping buffer of %u bytes",
GST_BUFFER_SIZE (buf));
mpegvideoparse->need_discont = TRUE;
gst_buffer_unref (buf);
buf = NULL;
}
}
}
if (buf != NULL) {
GST_DEBUG_OBJECT (mpegvideoparse,
"mpegvideoparse: pushing buffer of %u bytes with ts %"
GST_TIME_FORMAT, GST_BUFFER_SIZE (buf),
GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (buf)));
gst_buffer_set_caps (buf, GST_PAD_CAPS (mpegvideoparse->srcpad));
if (mpegvideoparse->need_discont) {
GST_DEBUG_OBJECT (mpegvideoparse,
"setting discont flag on outgoing buffer");
GST_BUFFER_FLAG_SET (buf, GST_BUFFER_FLAG_DISCONT);
mpegvideoparse->need_discont = FALSE;
}
mpv_send_pending_segs (mpegvideoparse);
res = gst_pad_push (mpegvideoparse->srcpad, buf);
buf = NULL;
}
/* Advance to the next data block */
mpeg_packetiser_next_block (&mpegvideoparse->packer);
cur = mpeg_packetiser_get_block (&mpegvideoparse->packer, &buf);
}
if (buf != NULL)
gst_buffer_unref (buf);
return res;
}
static GstFlowReturn
gst_mpegvideoparse_chain_forward (MpegVideoParse * mpegvideoparse,
gboolean discont, GstBuffer * buf)
{
GstFlowReturn res;
guint64 next_offset = GST_BUFFER_OFFSET_NONE;
GST_DEBUG_OBJECT (mpegvideoparse,
"mpegvideoparse: received buffer of %u bytes with ts %"
GST_TIME_FORMAT " and offset %" G_GINT64_FORMAT, GST_BUFFER_SIZE (buf),
GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (buf)), GST_BUFFER_OFFSET (buf));
/* If we have an offset, and the incoming offset doesn't match,
or we have a discont, handle it first by flushing out data
we have collected. */
if (mpegvideoparse->next_offset != GST_BUFFER_OFFSET_NONE) {
if (GST_BUFFER_OFFSET_IS_VALID (buf)) {
if (mpegvideoparse->next_offset != GST_BUFFER_OFFSET (buf))
discont = TRUE;
next_offset = GST_BUFFER_OFFSET (buf) + GST_BUFFER_SIZE (buf);
} else {
next_offset = mpegvideoparse->next_offset + GST_BUFFER_SIZE (buf);
}
}
/* Clear out any existing stuff if the new buffer is discontinuous */
if (discont) {
GST_DEBUG_OBJECT (mpegvideoparse, "Have discont packet, draining data");
mpegvideoparse->need_discont = TRUE;
mpeg_packetiser_handle_eos (&mpegvideoparse->packer);
res = mpegvideoparse_drain_avail (mpegvideoparse);
mpeg_packetiser_flush (&mpegvideoparse->packer);
if (res != GST_FLOW_OK) {
gst_buffer_unref (buf);
goto done;
}
}
/* Takes ownership of the data */
mpeg_packetiser_add_buf (&mpegvideoparse->packer, buf);
/* And push out what we can */
res = mpegvideoparse_drain_avail (mpegvideoparse);
done:
/* Update our offset */
mpegvideoparse->next_offset = next_offset;
return res;
}
/* scan the decode queue for a picture header with an I frame and return the
* index in the first buffer. We only scan the first buffer and possibly a
* couple of bytes of the next buffers to find the I frame. Scanning is done
* backwards because the first buffer could contain many picture start codes
* with I frames. */
static guint
scan_keyframe (MpegVideoParse * mpegvideoparse)
{
guint64 scanword;
guint count;
GList *walk;
GstBuffer *head;
guint8 *data;
guint size;
/* we use an 8 byte buffer, this is enough to hold the picture start code and
* the picture header bits we are interested in. We init to 0xff so that when
* we have a valid picture start without the header bits, we will be able to
* detect this because it will generate an invalid picture type. */
scanword = ~G_GUINT64_CONSTANT (0);
GST_LOG_OBJECT (mpegvideoparse, "scan keyframe");
/* move to the second buffer if we can, we should have at least one buffer */
walk = mpegvideoparse->decode;
g_return_val_if_fail (walk != NULL, -1);
head = GST_BUFFER_CAST (walk->data);
count = 0;
walk = g_list_next (walk);
while (walk) {
GstBuffer *buf = GST_BUFFER_CAST (walk->data);
data = GST_BUFFER_DATA (buf);
size = GST_BUFFER_SIZE (buf);
GST_LOG_OBJECT (mpegvideoparse, "collect remaining %d bytes from %p",
6 - count, buf);
while (size > 0 && count < 6) {
scanword = (scanword << 8) | *data++;
size--;
count++;
}
if (count == 6)
break;
walk = g_list_next (walk);
}
/* move bits to the beginning of the word now */
if (count)
scanword = (scanword << (8 * (8 - count)));
GST_LOG_OBJECT (mpegvideoparse, "scanword 0x%016" G_GINT64_MODIFIER "x",
scanword);
data = GST_BUFFER_DATA (head);
size = GST_BUFFER_SIZE (head);
while (size > 0) {
scanword = (((guint64) data[size - 1]) << 56) | (scanword >> 8);
GST_LOG_OBJECT (mpegvideoparse,
"scanword at %d 0x%016" G_GINT64_MODIFIER "x", size - 1, scanword);
/* check picture start and picture type */
if ((scanword & G_GUINT64_CONSTANT (0xffffffff00380000)) ==
G_GUINT64_CONSTANT (0x0000010000080000))
break;
size--;
}
return size - 1;
}
/* For reverse playback we use a technique that can be used for
* any keyframe based video codec.
*
* Input:
* Buffer decoding order: 7 8 9 4 5 6 1 2 3 EOS
* Keyframe flag: K K
* Discont flag: D D D
*
* - Each Discont marks a discont in the decoding order.
* - The keyframes mark where we can start decoding. For mpeg they are either
* set by the demuxer or we have to scan the buffers for a syncword and
* picture header with an I frame.
*
* First we prepend incomming buffers to the gather queue, whenever we receive
* a discont, we flush out the gather queue.
*
* The above data will be accumulated in the gather queue like this:
*
* gather queue: 9 8 7
* D
*
* Whe buffer 4 is received (with a DISCONT), we flush the gather queue like
* this:
*
* while (gather)
* take head of queue and prepend to decode queue.
* if we copied a keyframe, decode the decode queue.
*
* After we flushed the gather queue, we add 4 to the (now empty) gather queue.
* We get the following situation:
*
* gather queue: 4
* decode queue: 7 8 9
*
* After we received 5 (Keyframe) and 6:
*
* gather queue: 6 5 4
* decode queue: 7 8 9
*
* When we receive 1 (DISCONT) which triggers a flush of the gather queue:
*
* Copy head of the gather queue (6) to decode queue:
*
* gather queue: 5 4
* decode queue: 6 7 8 9
*
* Copy head of the gather queue (5) to decode queue. This is a keyframe so we
* can start decoding.
*
* gather queue: 4
* decode queue: 5 6 7 8 9
*
* Decode frames in decode queue, we don't actually do the decoding but we
* will send the decode queue to the downstream element. This will empty the
* decoding queue again.
*
* Copy head of the gather queue (4) to decode queue, we flushed the gather
* queue and can now store input buffer in the gather queue:
*
* gather queue: 1
* decode queue: 4
*
* When we receive EOS, the queue looks like:
*
* gather queue: 3 2 1
* decode queue: 4
*
* Fill decode queue, first keyframe we copy is 2:
*
* gather queue: 1
* decode queue: 2 3 4
*
* After pushing the decode queue:
*
* gather queue: 1
* decode queue:
*
* Leftover buffer 1 cannot be decoded and must be discarded.
*/
static GstFlowReturn
gst_mpegvideoparse_flush_decode (MpegVideoParse * mpegvideoparse, guint idx)
{
GstFlowReturn res = GST_FLOW_OK;
GstBuffer *head = NULL;
while (mpegvideoparse->decode) {
GstBuffer *buf;
buf = GST_BUFFER_CAST (mpegvideoparse->decode->data);
if (idx != -1) {
GstBuffer *temp;
if (idx > 0) {
/* first buffer, split at the point where the picture start was
* detected and store as the new head of the decoding list. */
head = gst_buffer_create_sub (buf, 0, idx);
/* push the remainder after the picture sync point downstream, this is the
* first DISCONT buffer we push. */
temp = gst_buffer_create_sub (buf, idx, GST_BUFFER_SIZE (buf) - idx);
/* don't need old buffer anymore and swap new buffer */
gst_buffer_unref (buf);
buf = temp;
}
GST_BUFFER_FLAG_SET (buf, GST_BUFFER_FLAG_DISCONT);
idx = -1;
} else {
/* next buffers are not discont */
GST_BUFFER_FLAG_UNSET (buf, GST_BUFFER_FLAG_DISCONT);
}
GST_DEBUG_OBJECT (mpegvideoparse, "pushing buffer %p, ts %" GST_TIME_FORMAT,
buf, GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (buf)));
res = gst_pad_push (mpegvideoparse->srcpad, buf);
mpegvideoparse->decode =
g_list_delete_link (mpegvideoparse->decode, mpegvideoparse->decode);
}
if (head) {
/* store remainder of the buffer */
mpegvideoparse->decode = g_list_prepend (mpegvideoparse->decode, head);
}
return res;
}
static GstFlowReturn
gst_mpegvideoparse_chain_reverse (MpegVideoParse * mpegvideoparse,
gboolean discont, GstBuffer * buf)
{
GstFlowReturn res = GST_FLOW_OK;
/* if we have a discont, move buffers to the decode list */
if (G_UNLIKELY (discont)) {
GST_DEBUG_OBJECT (mpegvideoparse, "received discont,gathering buffers");
while (mpegvideoparse->gather) {
GstBuffer *gbuf;
guint keyframeidx;
gbuf = GST_BUFFER_CAST (mpegvideoparse->gather->data);
/* remove from the gather list */
mpegvideoparse->gather =
g_list_delete_link (mpegvideoparse->gather, mpegvideoparse->gather);
/* copy to decode queue */
mpegvideoparse->decode = g_list_prepend (mpegvideoparse->decode, gbuf);
GST_DEBUG_OBJECT (mpegvideoparse, "copied decoding buffer %p, len %d",
gbuf, g_list_length (mpegvideoparse->decode));
/* check if we copied a keyframe, we scan the buffers on the decode queue.
* We only need to scan the first buffer and at most 3 bytes of the second
* buffer. We return the index of the keyframe (or -1 when nothing was
* found) */
while ((keyframeidx = scan_keyframe (mpegvideoparse)) != -1) {
GST_DEBUG_OBJECT (mpegvideoparse, "copied keyframe at %u", keyframeidx);
res = gst_mpegvideoparse_flush_decode (mpegvideoparse, keyframeidx);
}
}
}
if (buf) {
/* add buffer to gather queue */
GST_DEBUG_OBJECT (mpegvideoparse, "gathering buffer %p, size %u", buf,
GST_BUFFER_SIZE (buf));
mpegvideoparse->gather = g_list_prepend (mpegvideoparse->gather, buf);
}
return res;
}
static GstFlowReturn
gst_mpegvideoparse_chain (GstPad * pad, GstBuffer * buf)
{
MpegVideoParse *mpegvideoparse;
GstFlowReturn res;
gboolean discont;
mpegvideoparse =
GST_MPEGVIDEOPARSE (gst_object_get_parent (GST_OBJECT (pad)));
discont = GST_BUFFER_IS_DISCONT (buf);
if (mpegvideoparse->segment.rate > 0.0)
res = gst_mpegvideoparse_chain_forward (mpegvideoparse, discont, buf);
else
res = gst_mpegvideoparse_chain_reverse (mpegvideoparse, discont, buf);
gst_object_unref (mpegvideoparse);
return res;
}
static gboolean
mpv_parse_sink_event (GstPad * pad, GstEvent * event)
{
gboolean res = TRUE;
MpegVideoParse *mpegvideoparse =
GST_MPEGVIDEOPARSE (gst_pad_get_parent (pad));
switch (GST_EVENT_TYPE (event)) {
case GST_EVENT_NEWSEGMENT:
{
gdouble rate, applied_rate;
GstFormat format;
gint64 start, stop, pos;
gboolean update;
gst_event_parse_new_segment_full (event, &update, &rate, &applied_rate,
&format, &start, &stop, &pos);
if (format == GST_FORMAT_BYTES) {
/* FIXME: Later, we might use a seek table to seek on elementary stream
files, and that would allow byte-to-time conversions. It's not a high
priority - most mpeg video is muxed and then the demuxer handles
seeking. In the meantime, here's some commented out logic copied
from mp3parse */
#if 0
GstClockTime seg_start, seg_stop, seg_pos;
/* stop time is allowed to be open-ended, but not start & pos */
if (!mp3parse_bytepos_to_time (mp3parse, stop, &seg_stop))
seg_stop = GST_CLOCK_TIME_NONE;
if (mp3parse_bytepos_to_time (mp3parse, start, &seg_start) &&
mp3parse_bytepos_to_time (mp3parse, pos, &seg_pos)) {
gst_event_unref (event);
event = gst_event_new_new_segment_full (update, rate, applied_rate,
GST_FORMAT_TIME, seg_start, seg_stop, seg_pos);
format = GST_FORMAT_TIME;
GST_DEBUG_OBJECT (mp3parse, "Converted incoming segment to TIME. "
"start = %" G_GINT64_FORMAT ", stop = %" G_GINT64_FORMAT
"pos = %" G_GINT64_FORMAT, seg_start, seg_stop, seg_pos);
}
#endif
}
if (format != GST_FORMAT_TIME) {
/* Unknown incoming segment format. Output a default open-ended
* TIME segment */
gst_event_unref (event);
/* set new values */
format = GST_FORMAT_TIME;
start = 0;
stop = GST_CLOCK_TIME_NONE;
pos = 0;
/* create a new segment with these values */
event = gst_event_new_new_segment_full (update, rate, applied_rate,
format, start, stop, pos);
}
gst_mpegvideoparse_flush (mpegvideoparse);
/* now configure the values */
gst_segment_set_newsegment_full (&mpegvideoparse->segment, update,
rate, applied_rate, format, start, stop, pos);
GST_DEBUG_OBJECT (mpegvideoparse,
"Pushing newseg rate %g, applied rate %g, format %d, start %"
G_GINT64_FORMAT ", stop %" G_GINT64_FORMAT ", pos %" G_GINT64_FORMAT,
rate, applied_rate, format, start, stop, pos);
/* Forward the event if we've seen a sequence header
* and therefore set output caps, otherwise queue it for later */
if (mpegvideoparse->seq_hdr.mpeg_version != 0)
res = gst_pad_push_event (mpegvideoparse->srcpad, event);
else {
res = TRUE;
mpegvideoparse->pending_segs =
g_list_append (mpegvideoparse->pending_segs, event);
}
break;
}
case GST_EVENT_FLUSH_STOP:
GST_DEBUG_OBJECT (mpegvideoparse, "flush stop");
gst_mpegvideoparse_flush (mpegvideoparse);
res = gst_pad_push_event (mpegvideoparse->srcpad, event);
break;
case GST_EVENT_EOS:
/* Push any remaining buffers out, then flush. */
GST_DEBUG_OBJECT (mpegvideoparse, "received EOS");
if (mpegvideoparse->segment.rate >= 0.0) {
mpeg_packetiser_handle_eos (&mpegvideoparse->packer);
mpegvideoparse_drain_avail (mpegvideoparse);
gst_mpegvideoparse_flush (mpegvideoparse);
} else {
gst_mpegvideoparse_chain_reverse (mpegvideoparse, TRUE, NULL);
gst_mpegvideoparse_flush_decode (mpegvideoparse, 0);
}
res = gst_pad_push_event (mpegvideoparse->srcpad, event);
break;
default:
res = gst_pad_push_event (mpegvideoparse->srcpad, event);
break;
}
gst_object_unref (mpegvideoparse);
return res;
}
static GstStateChangeReturn
gst_mpegvideoparse_change_state (GstElement * element,
GstStateChange transition)
{
MpegVideoParse *mpegvideoparse;
GstStateChangeReturn ret;
g_return_val_if_fail (GST_IS_MPEGVIDEOPARSE (element),
GST_STATE_CHANGE_FAILURE);
mpegvideoparse = GST_MPEGVIDEOPARSE (element);
switch (transition) {
case GST_STATE_CHANGE_READY_TO_PAUSED:
gst_segment_init (&mpegvideoparse->segment, GST_FORMAT_UNDEFINED);
break;
default:
break;
}
ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
switch (transition) {
case GST_STATE_CHANGE_PAUSED_TO_READY:
mpv_parse_reset (mpegvideoparse);
gst_mpegvideoparse_flush (mpegvideoparse);
break;
default:
break;
}
return ret;
}
static gboolean
plugin_init (GstPlugin * plugin)
{
GST_DEBUG_CATEGORY_INIT (mpv_parse_debug, "legacympegvideoparse", 0,
"MPEG Video Parser");
return gst_element_register (plugin, "legacympegvideoparse",
GST_RANK_NONE, GST_TYPE_MPEGVIDEOPARSE);
}
GST_PLUGIN_DEFINE (GST_VERSION_MAJOR,
GST_VERSION_MINOR,
"mpegvideoparse",
"MPEG-1 and MPEG-2 video parser",
plugin_init, VERSION, GST_LICENSE, GST_PACKAGE_NAME, GST_PACKAGE_ORIGIN)
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