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gstreamer/gst/rtp/gstrtph261pay.c
Thibault Saunier 0a6a62aa76 docs: Port all docstring to gtk-doc markdown
2019-05-13 10:24:40 -04:00

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/* GStreamer
* Copyright (C) <2014> Stian Selnes <stian@pexip.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.
*
*/
/**
* SECTION:element-rtph261pay
* @title: rtph261pay
* @see_also: rtph261depay
*
* Payload encoded H.261 video frames into RTP packets according to RFC 4587.
* For detailed information see: https://www.rfc-editor.org/rfc/rfc4587.txt
*
* The payloader takes a H.261 frame, parses it and splits it into fragments
* on MB boundaries in order to match configured MTU size. For each fragment
* an RTP packet is constructed with an RTP packet header followed by the
* fragment. In addition the payloader will make sure the packetized H.261
* stream appears as a continuous bit-stream after depacketization by shifting
* the encoded bit-stream of a frame to align with the last significant bit of
* the previous frame. This helps interoperability in the case where the
* encoder does not produce a continuous bit-stream but the decoder requires
* it.
*
* ## Example launch line
* |[
* gst-launch-1.0 videotestsrc ! avenc_h261 ! rtph261pay ! udpsink
* ]| This will encode a test video and payload it. Refer to the rtph261depay
* example to depayload and play the RTP stream.
*
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include "gstrtph261pay.h"
#include "gstrtputils.h"
#include <gst/rtp/gstrtpbuffer.h>
#include <gst/video/video.h>
#include <gst/base/gstbitreader.h>
#include <string.h>
GST_DEBUG_CATEGORY_STATIC (rtph261pay_debug);
#define GST_CAT_DEFAULT (rtph261pay_debug)
#define GST_RTP_HEADER_LEN 12
#define GST_RTP_H261_PAYLOAD_HEADER_LEN 4
static GstStaticPadTemplate gst_rtp_h261_pay_sink_template =
GST_STATIC_PAD_TEMPLATE ("sink",
GST_PAD_SINK,
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("video/x-h261")
);
static GstStaticPadTemplate gst_rtp_h261_pay_src_template =
GST_STATIC_PAD_TEMPLATE ("src",
GST_PAD_SRC,
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("application/x-rtp, "
"media = (string) \"video\", "
"payload = (int) " GST_RTP_PAYLOAD_H261_STRING ", "
"clock-rate = (int) 90000, " "encoding-name = (string) \"H261\"; "
"application/x-rtp, "
"media = (string) \"video\", "
"payload = (int) " GST_RTP_PAYLOAD_DYNAMIC_STRING ", "
"clock-rate = (int) 90000, " "encoding-name = (string) \"H261\"")
);
G_DEFINE_TYPE (GstRtpH261Pay, gst_rtp_h261_pay, GST_TYPE_RTP_BASE_PAYLOAD);
#define parent_class gst_rtp_h261_pay_parent_class
typedef struct
{
guint32 mba;
guint32 mtype;
guint32 quant;
gint mvx;
gint mvy;
guint endpos;
gint gobn;
} Macroblock;
typedef struct
{
Macroblock last;
guint startpos;
guint endpos;
guint32 gn;
guint32 gquant;
} Gob;
#define PSC_LEN 20
#define TR_LEN 5
#define PTYPE_LEN 6
#define GBSC_LEN 16
#define GN_LEN 4
#define GQUANT_LEN 5
#define GEI_LEN 1
#define GSPARE_LEN 8
#define MQUANT_LEN 5
#define MAX_NUM_GOB 12
typedef enum
{
PARSE_END_OF_BUFFER = -2,
PARSE_ERROR = -1,
PARSE_OK = 0,
PARSE_END_OF_FRAME,
PARSE_END_OF_GOB,
} ParseReturn;
#define SKIP_BITS(br,nbits) G_STMT_START { \
if (!gst_bit_reader_skip (br, nbits)) \
return PARSE_END_OF_BUFFER; \
} G_STMT_END
#define GET_BITS(br,val,nbits) G_STMT_START { \
if (!gst_bit_reader_get_bits_uint32 (br, val, nbits)) \
return PARSE_END_OF_BUFFER; \
} G_STMT_END
/* Unchecked since we peek outside the buffer. Ok because of padding. */
#define PEEK_BITS(br,val,nbits) G_STMT_START { \
*val = gst_bit_reader_peek_bits_uint16_unchecked (br, nbits); \
} G_STMT_END
#define MBA_STUFFING 34
#define MBA_START_CODE 35
#define MBA_LEN 35
#define MBA_WID 4
/* [code, mask, nbits, mba] */
static const guint16 mba_table[MBA_LEN][MBA_WID] = {
{0x8000, 0x8000, 1, 1},
{0x6000, 0xe000, 3, 2},
{0x4000, 0xe000, 3, 3},
{0x3000, 0xf000, 4, 4},
{0x2000, 0xf000, 4, 5},
{0x1800, 0xf800, 5, 6},
{0x1000, 0xf800, 5, 7},
{0x0e00, 0xfe00, 7, 8},
{0x0c00, 0xfe00, 7, 9},
{0x0b00, 0xff00, 8, 10},
{0x0a00, 0xff00, 8, 11},
{0x0900, 0xff00, 8, 12},
{0x0800, 0xff00, 8, 13},
{0x0700, 0xff00, 8, 14},
{0x0600, 0xff00, 8, 15},
{0x05c0, 0xffc0, 10, 16},
{0x0580, 0xffc0, 10, 17},
{0x0540, 0xffc0, 10, 18},
{0x0500, 0xffc0, 10, 19},
{0x04c0, 0xffc0, 10, 20},
{0x0480, 0xffc0, 10, 21},
{0x0460, 0xffe0, 11, 22},
{0x0440, 0xffe0, 11, 23},
{0x0420, 0xffe0, 11, 24},
{0x0400, 0xffe0, 11, 25},
{0x03e0, 0xffe0, 11, 26},
{0x03c0, 0xffe0, 11, 27},
{0x03a0, 0xffe0, 11, 28},
{0x0380, 0xffe0, 11, 29},
{0x0360, 0xffe0, 11, 30},
{0x0340, 0xffe0, 11, 31},
{0x0320, 0xffe0, 11, 32},
{0x0300, 0xffe0, 11, 33},
{0x01e0, 0xffe0, 11, MBA_STUFFING},
{0x0001, 0xffff, 16, MBA_START_CODE},
};
#define MTYPE_INTRA (1 << 0)
#define MTYPE_INTER (1 << 1)
#define MTYPE_MC (1 << 2)
#define MTYPE_FIL (1 << 3)
#define MTYPE_MQUANT (1 << 4)
#define MTYPE_MVD (1 << 5)
#define MTYPE_CBP (1 << 6)
#define MTYPE_TCOEFF (1 << 7)
#define MTYPE_LEN 10
#define MTYPE_WID 4
/* [code, mask, nbits, flags] */
static const guint16 mtype_table[MTYPE_LEN][MTYPE_WID] = {
{0x8000, 0x8000, 1, MTYPE_INTER | MTYPE_CBP | MTYPE_TCOEFF},
{0x4000, 0xc000, 2,
MTYPE_INTER | MTYPE_MC | MTYPE_FIL | MTYPE_MVD | MTYPE_CBP |
MTYPE_TCOEFF},
{0x2000, 0xe000, 3, MTYPE_INTER | MTYPE_MC | MTYPE_FIL | MTYPE_MVD},
{0x1000, 0xf000, 4, MTYPE_INTRA | MTYPE_TCOEFF},
{0x0800, 0xf800, 5, MTYPE_INTER | MTYPE_MQUANT | MTYPE_CBP | MTYPE_TCOEFF},
{0x0400, 0xfc00, 6,
MTYPE_INTER | MTYPE_MC | MTYPE_FIL | MTYPE_MQUANT | MTYPE_MVD |
MTYPE_CBP | MTYPE_TCOEFF},
{0x0200, 0xfe00, 7, MTYPE_INTRA | MTYPE_MQUANT | MTYPE_TCOEFF},
{0x0100, 0xff00, 8,
MTYPE_INTER | MTYPE_MC | MTYPE_MVD | MTYPE_CBP | MTYPE_TCOEFF},
{0x0080, 0xff80, 9, MTYPE_INTER | MTYPE_MC | MTYPE_MVD},
{0x0040, 0xffc0, 10,
MTYPE_INTER | MTYPE_MC | MTYPE_MQUANT | MTYPE_MVD | MTYPE_CBP |
MTYPE_TCOEFF},
};
#define MVD_LEN 32
#define MVD_WID 5
/* [code, mask, nbits, mvd1, mvd2] */
static const guint16 mvd_table[MVD_LEN][MVD_WID] = {
{0x8000, 0x8000, 1, 0, 0},
{0x6000, 0xe000, 3, -1, -1},
{0x4000, 0xe000, 3, 1, 1},
{0x3000, 0xf000, 4, -2, 30},
{0x2000, 0xf000, 4, 2, -30},
{0x1800, 0xf800, 5, -3, 29},
{0x1000, 0xf800, 5, 3, -29},
{0x0e00, 0xfe00, 7, -4, 28},
{0x0c00, 0xfe00, 7, 4, -28},
{0x0700, 0xff00, 8, -7, 25},
{0x0900, 0xff00, 8, -6, 26},
{0x0b00, 0xff00, 8, -5, 27},
{0x0a00, 0xff00, 8, 5, -27},
{0x0800, 0xff00, 8, 6, -26},
{0x0600, 0xff00, 8, 7, -25},
{0x04c0, 0xffc0, 10, -10, 22},
{0x0540, 0xffc0, 10, -9, 23},
{0x05c0, 0xffc0, 10, -8, 24},
{0x0580, 0xffc0, 10, 8, -24},
{0x0500, 0xffc0, 10, 9, -23},
{0x0480, 0xffc0, 10, 10, -22},
{0x0320, 0xffe0, 11, -16, 16},
{0x0360, 0xffe0, 11, -15, 17},
{0x03a0, 0xffe0, 11, -14, 18},
{0x03e0, 0xffe0, 11, -13, 19},
{0x0420, 0xffe0, 11, -12, 20},
{0x0460, 0xffe0, 11, -11, 21},
{0x0440, 0xffe0, 11, 11, -21},
{0x0400, 0xffe0, 11, 12, -20},
{0x03c0, 0xffe0, 11, 13, -19},
{0x0380, 0xffe0, 11, 14, -18},
{0x0340, 0xffe0, 11, 15, -17},
};
#define CBP_LEN 63
/* [code, mask, nbits, cbp] */
static const guint16 cbp_table[CBP_LEN][4] = {
{0xe000, 0xe000, 3, 60},
{0xd000, 0xf000, 4, 4},
{0xc000, 0xf000, 4, 8},
{0xb000, 0xf000, 4, 16},
{0xa000, 0xf000, 4, 32},
{0x9800, 0xf800, 5, 12},
{0x9000, 0xf800, 5, 48},
{0x8800, 0xf800, 5, 20},
{0x8000, 0xf800, 5, 40},
{0x7800, 0xf800, 5, 28},
{0x7000, 0xf800, 5, 44},
{0x6800, 0xf800, 5, 52},
{0x6000, 0xf800, 5, 56},
{0x5800, 0xf800, 5, 1},
{0x5000, 0xf800, 5, 61},
{0x4800, 0xf800, 5, 2},
{0x4000, 0xf800, 5, 62},
{0x3c00, 0xfc00, 6, 24},
{0x3800, 0xfc00, 6, 36},
{0x3400, 0xfc00, 6, 3},
{0x3000, 0xfc00, 6, 63},
{0x2e00, 0xfe00, 7, 5},
{0x2c00, 0xfe00, 7, 9},
{0x2a00, 0xfe00, 7, 17},
{0x2800, 0xfe00, 7, 33},
{0x2600, 0xfe00, 7, 6},
{0x2400, 0xfe00, 7, 10},
{0x2200, 0xfe00, 7, 18},
{0x2000, 0xfe00, 7, 34},
{0x1f00, 0xff00, 8, 7},
{0x1e00, 0xff00, 8, 11},
{0x1d00, 0xff00, 8, 19},
{0x1c00, 0xff00, 8, 35},
{0x1b00, 0xff00, 8, 13},
{0x1a00, 0xff00, 8, 49},
{0x1900, 0xff00, 8, 21},
{0x1800, 0xff00, 8, 41},
{0x1700, 0xff00, 8, 14},
{0x1600, 0xff00, 8, 50},
{0x1500, 0xff00, 8, 22},
{0x1400, 0xff00, 8, 42},
{0x1300, 0xff00, 8, 15},
{0x1200, 0xff00, 8, 51},
{0x1100, 0xff00, 8, 23},
{0x1000, 0xff00, 8, 43},
{0x0f00, 0xff00, 8, 25},
{0x0e00, 0xff00, 8, 37},
{0x0d00, 0xff00, 8, 26},
{0x0c00, 0xff00, 8, 38},
{0x0b00, 0xff00, 8, 29},
{0x0a00, 0xff00, 8, 45},
{0x0900, 0xff00, 8, 53},
{0x0800, 0xff00, 8, 57},
{0x0700, 0xff00, 8, 30},
{0x0600, 0xff00, 8, 46},
{0x0500, 0xff00, 8, 54},
{0x0400, 0xff00, 8, 58},
{0x0380, 0xff80, 9, 31},
{0x0300, 0xff80, 9, 47},
{0x0280, 0xff80, 9, 55},
{0x0200, 0xff80, 9, 59},
{0x0180, 0xff80, 9, 27},
{0x0100, 0xff80, 9, 39},
};
#define TCOEFF_EOB 0xffff
#define TCOEFF_ESC 0xfffe
#define TCOEFF_LEN 65
/* [code, mask, nbits, run, level] */
static const guint16 tcoeff_table[TCOEFF_LEN][5] = {
{0x8000, 0xc000, 2, TCOEFF_EOB, 0}, /* Not available for first coeff */
/* {0x8000, 0x8000, 2, 0, 1}, *//* Available only for first Inter coeff */
{0xc000, 0xc000, 3, 0, 1}, /* Not available for first coeff */
{0x6000, 0xe000, 4, 1, 1},
{0x4000, 0xf000, 5, 0, 2},
{0x5000, 0xf000, 5, 2, 1},
{0x2800, 0xf800, 6, 0, 3},
{0x3800, 0xf800, 6, 3, 1},
{0x3000, 0xf800, 6, 4, 1},
{0x0400, 0xfc00, 6, TCOEFF_ESC, 0},
{0x1800, 0xfc00, 7, 1, 2},
{0x1c00, 0xfc00, 7, 5, 1},
{0x1400, 0xfc00, 7, 6, 1},
{0x1000, 0xfc00, 7, 7, 1},
{0x0c00, 0xfe00, 8, 0, 4},
{0x0800, 0xfe00, 8, 2, 2},
{0x0e00, 0xfe00, 8, 8, 1},
{0x0a00, 0xfe00, 8, 9, 1},
{0x2600, 0xff00, 9, 0, 5},
{0x2100, 0xff00, 9, 0, 6},
{0x2500, 0xff00, 9, 1, 3},
{0x2400, 0xff00, 9, 3, 2},
{0x2700, 0xff00, 9, 10, 1},
{0x2300, 0xff00, 9, 11, 1},
{0x2200, 0xff00, 9, 12, 1},
{0x2000, 0xff00, 9, 13, 1},
{0x0280, 0xffc0, 11, 0, 7},
{0x0300, 0xffc0, 11, 1, 4},
{0x02c0, 0xffc0, 11, 2, 3},
{0x03c0, 0xffc0, 11, 4, 2},
{0x0240, 0xffc0, 11, 5, 2},
{0x0380, 0xffc0, 11, 14, 1},
{0x0340, 0xffc0, 11, 15, 1},
{0x0200, 0xffc0, 11, 16, 1},
{0x01d0, 0xfff0, 13, 0, 8},
{0x0180, 0xfff0, 13, 0, 9},
{0x0130, 0xfff0, 13, 0, 10},
{0x0100, 0xfff0, 13, 0, 11},
{0x01b0, 0xfff0, 13, 1, 5},
{0x0140, 0xfff0, 13, 2, 4},
{0x01c0, 0xfff0, 13, 3, 3},
{0x0120, 0xfff0, 13, 4, 3},
{0x01e0, 0xfff0, 13, 6, 2},
{0x0150, 0xfff0, 13, 7, 2},
{0x0110, 0xfff0, 13, 8, 2},
{0x01f0, 0xfff0, 13, 17, 1},
{0x01a0, 0xfff0, 13, 18, 1},
{0x0190, 0xfff0, 13, 19, 1},
{0x0170, 0xfff0, 13, 20, 1},
{0x0160, 0xfff0, 13, 21, 1},
{0x00d0, 0xfff8, 14, 0, 12},
{0x00c8, 0xfff8, 14, 0, 13},
{0x00c0, 0xfff8, 14, 0, 14},
{0x00b8, 0xfff8, 14, 0, 15},
{0x00b0, 0xfff8, 14, 1, 6},
{0x00a8, 0xfff8, 14, 1, 7},
{0x00a0, 0xfff8, 14, 2, 5},
{0x0098, 0xfff8, 14, 3, 4},
{0x0090, 0xfff8, 14, 5, 3},
{0x0088, 0xfff8, 14, 9, 2},
{0x0080, 0xfff8, 14, 10, 2},
{0x00f8, 0xfff8, 14, 22, 1},
{0x00f0, 0xfff8, 14, 23, 1},
{0x00e8, 0xfff8, 14, 24, 1},
{0x00e0, 0xfff8, 14, 25, 1},
{0x00d8, 0xfff8, 14, 26, 1},
};
static ParseReturn
decode_mba (GstBitReader * br, gint * mba)
{
gint i;
guint16 code;
*mba = -1;
do {
PEEK_BITS (br, &code, 16);
for (i = 0; i < MBA_LEN; i++) {
if ((code & mba_table[i][1]) == mba_table[i][0]) {
*mba = mba_table[i][3];
if (*mba == MBA_START_CODE)
return PARSE_END_OF_GOB;
SKIP_BITS (br, mba_table[i][2]);
if (*mba != MBA_STUFFING)
return PARSE_OK;
}
}
} while (*mba == MBA_STUFFING);
/* 0x0 indicates end of frame since we appended 0-bytes */
if (code == 0x0)
return PARSE_END_OF_FRAME;
return PARSE_ERROR;
}
static ParseReturn
decode_mtype (GstBitReader * br, guint * mtype)
{
gint i;
guint16 code;
PEEK_BITS (br, &code, 16);
for (i = 0; i < MTYPE_LEN; i++) {
if ((code & mtype_table[i][1]) == mtype_table[i][0]) {
SKIP_BITS (br, mtype_table[i][2]);
*mtype = mtype_table[i][3];
return PARSE_OK;
}
}
return PARSE_ERROR;
}
static ParseReturn
decode_mvd (GstBitReader * br, gint * mvd1, gint * mvd2)
{
gint i;
guint16 code;
PEEK_BITS (br, &code, 16);
for (i = 0; i < MVD_LEN; i++) {
if ((code & mvd_table[i][1]) == mvd_table[i][0]) {
SKIP_BITS (br, mvd_table[i][2]);
*mvd1 = (gint16) mvd_table[i][3];
*mvd2 = (gint16) mvd_table[i][4];
return PARSE_OK;
}
}
return PARSE_ERROR;
}
static ParseReturn
decode_cbp (GstBitReader * br, guint * cbp)
{
gint i;
guint16 code;
PEEK_BITS (br, &code, 16);
for (i = 0; i < CBP_LEN; i++) {
if ((code & cbp_table[i][1]) == cbp_table[i][0]) {
SKIP_BITS (br, cbp_table[i][2]);
*cbp = cbp_table[i][3];
return PARSE_OK;
}
}
return PARSE_ERROR;
}
static ParseReturn
decode_tcoeff (GstBitReader * br, guint mtype)
{
gint i;
guint16 code;
gboolean eob;
/* Special handling of first coeff */
if (mtype & MTYPE_INTER) {
/* Inter, different vlc since EOB is not allowed */
PEEK_BITS (br, &code, 16);
if (code & 0x8000) {
SKIP_BITS (br, 2);
GST_TRACE ("tcoeff first inter special");
} else {
/* Fallthrough. Let the first coeff be handled like other coeffs since
* the vlc is the same as long as the first bit is not set. */
}
} else {
/* Intra, first coeff is fixed 8-bit */
GST_TRACE ("tcoeff first intra special");
SKIP_BITS (br, 8);
}
/* Block must end with EOB. */
eob = FALSE;
while (!eob) {
PEEK_BITS (br, &code, 16);
for (i = 0; i < TCOEFF_LEN; i++) {
if ((code & tcoeff_table[i][1]) == tcoeff_table[i][0]) {
GST_TRACE ("tcoeff vlc[%d], run=%d, level=%d", i, tcoeff_table[i][3],
tcoeff_table[i][4]);
SKIP_BITS (br, tcoeff_table[i][2]);
if (tcoeff_table[i][3] == TCOEFF_EOB) {
eob = TRUE;
} else if (tcoeff_table[i][3] == TCOEFF_ESC) {
#if 0
guint16 val;
val = gst_bit_reader_peek_bits_uint16_unchecked (br, 6 + 8);
GST_TRACE ("esc run=%d, level=%d", val >> 8, (gint8) (val & 0xff));
#endif
SKIP_BITS (br, 6 + 8);
}
break;
}
}
if (i == TCOEFF_LEN)
/* No matching VLC */
return PARSE_ERROR;
}
return PARSE_OK;
}
static gint
find_picture_header_offset (const guint8 * data, gsize size)
{
gint i;
guint32 val;
if (size < 4)
return -1;
val = GST_READ_UINT32_BE (data);
for (i = 0; i < 8; i++) {
if ((val >> (12 - i)) == 0x10)
return i;
}
return -1;
}
static ParseReturn
parse_picture_header (GstRtpH261Pay * pay, GstBitReader * br, gint * num_gob)
{
guint32 val;
GET_BITS (br, &val, PSC_LEN);
if (val != 0x10)
return PARSE_ERROR;
SKIP_BITS (br, TR_LEN);
GET_BITS (br, &val, PTYPE_LEN);
*num_gob = (val & 0x04) == 0 ? 3 : 12;
return PARSE_OK;
}
static ParseReturn
parse_gob_header (GstRtpH261Pay * pay, GstBitReader * br, Gob * gob)
{
guint32 val;
GET_BITS (br, &val, GBSC_LEN);
if (val != 0x01)
return PARSE_ERROR;
GET_BITS (br, &gob->gn, GN_LEN);
GST_TRACE_OBJECT (pay, "Parsing GOB %d", gob->gn);
GET_BITS (br, &gob->gquant, GQUANT_LEN);
GST_TRACE_OBJECT (pay, "GQUANT %d", gob->gquant);
GET_BITS (br, &val, GEI_LEN);
while (val != 0) {
SKIP_BITS (br, GSPARE_LEN);
GET_BITS (br, &val, GEI_LEN);
}
return PARSE_OK;
}
static ParseReturn
parse_mb (GstRtpH261Pay * pay, GstBitReader * br, const Macroblock * prev,
Macroblock * mb)
{
gint mba_diff;
guint cbp;
ParseReturn ret;
cbp = 0x3f;
mb->quant = prev->quant;
if ((ret = decode_mba (br, &mba_diff)) != PARSE_OK)
return ret;
mb->mba = prev->mba == 0 ? mba_diff : prev->mba + mba_diff;
GST_TRACE_OBJECT (pay, "Parse MBA %d (mba_diff %d)", mb->mba, mba_diff);
if ((ret = decode_mtype (br, &mb->mtype)) != PARSE_OK)
return ret;
GST_TRACE_OBJECT (pay,
"MTYPE: inter %d, mc %d, fil %d, mquant %d, mvd %d, cbp %d, tcoeff %d",
(mb->mtype & MTYPE_INTER) != 0, (mb->mtype & MTYPE_MC) != 0,
(mb->mtype & MTYPE_FIL) != 0, (mb->mtype & MTYPE_MQUANT) != 0,
(mb->mtype & MTYPE_MVD) != 0, (mb->mtype & MTYPE_CBP) != 0,
(mb->mtype & MTYPE_TCOEFF) != 0);
if (mb->mtype & MTYPE_MQUANT) {
GET_BITS (br, &mb->quant, MQUANT_LEN);
GST_TRACE_OBJECT (pay, "MQUANT: %d", mb->quant);
}
if (mb->mtype & MTYPE_MVD) {
gint i, pmv[2], mv[2];
if (mb->mba == 1 || mb->mba == 12 || mb->mba == 23 || mba_diff != 1 ||
(prev->mtype & MTYPE_INTER) == 0) {
pmv[0] = 0;
pmv[1] = 0;
} else {
pmv[0] = prev->mvx;
pmv[1] = prev->mvy;
}
for (i = 0; i < 2; i++) {
gint mvd1, mvd2;
if ((ret = decode_mvd (br, &mvd1, &mvd2)) != PARSE_OK)
return ret;
if (ABS (pmv[i] + mvd1) <= 15)
mv[i] = pmv[i] + mvd1;
else
mv[i] = pmv[i] + mvd2;
}
mb->mvx = mv[0];
mb->mvy = mv[1];
} else {
mb->mvx = 0;
mb->mvy = 0;
}
if (mb->mtype & MTYPE_CBP) {
if ((ret = decode_cbp (br, &cbp)) != PARSE_OK)
return ret;
}
/* Block layer */
if (mb->mtype & MTYPE_TCOEFF) {
gint block;
for (block = 0; block < 6; block++) {
if (cbp & (1 << (5 - block))) {
GST_TRACE_OBJECT (pay, "Decode TCOEFF for block %d", block);
if ((ret = decode_tcoeff (br, mb->mtype)) != PARSE_OK)
return ret;
}
}
}
mb->endpos = gst_bit_reader_get_pos (br);
return ret;
}
/* Parse macroblocks until the next MB that exceeds maxpos. At least one MB is
* included even if it exceeds maxpos. Returns endpos of last included MB. */
static ParseReturn
parse_mb_until_pos (GstRtpH261Pay * pay, GstBitReader * br, Gob * gob,
guint * endpos)
{
ParseReturn ret;
gint count = 0;
gboolean stop = FALSE;
guint maxpos = *endpos;
Macroblock mb;
GST_LOG_OBJECT (pay, "Parse until pos %u, start at pos %u, gobn %d, mba %d",
maxpos, gst_bit_reader_get_pos (br), gob->gn, gob->last.mba);
while (!stop) {
ret = parse_mb (pay, br, &gob->last, &mb);
switch (ret) {
case PARSE_OK:
if (mb.endpos > maxpos && count > 0) {
/* Don't include current MB */
stop = TRUE;
} else {
/* Update to include current MB */
*endpos = mb.endpos;
gob->last = mb;
count++;
}
break;
case PARSE_END_OF_FRAME:
*endpos = gst_bit_reader_get_pos (br);
GST_DEBUG_OBJECT (pay, "End of frame at pos %u (last GOBN %d MBA %d)",
*endpos, gob->gn, gob->last.mba);
stop = TRUE;
break;
case PARSE_END_OF_GOB:
/* Note that a GOB can contain nothing, so we may get here on the first
* iteration. */
*endpos = gob->last.mba == 0 ?
gob->startpos : gst_bit_reader_get_pos (br);
GST_DEBUG_OBJECT (pay, "End of gob at pos %u (last GOBN %d MBA %d)",
*endpos, gob->gn, gob->last.mba);
stop = TRUE;
break;
case PARSE_END_OF_BUFFER:
case PARSE_ERROR:
GST_WARNING_OBJECT (pay, "Failed to parse stream (reason %d)", ret);
return ret;
break;
default:
g_assert_not_reached ();
break;
}
}
gob->last.gobn = gob->gn;
if (ret == PARSE_OK) {
GST_DEBUG_OBJECT (pay,
"Split GOBN %d after MBA %d (endpos %u, maxpos %u, nextpos %u)",
gob->gn, gob->last.mba, *endpos, maxpos, mb.endpos);
gst_bit_reader_set_pos (br, *endpos);
}
return ret;
}
static guint
bitrange_to_bytes (guint first, guint last)
{
return (GST_ROUND_UP_8 (last) - GST_ROUND_DOWN_8 (first)) / 8;
}
/* Find next 16-bit GOB start code (0x0001), which may not be byte aligned.
* Returns the bit offset of the first bit of GBSC. */
static gssize
find_gob (GstRtpH261Pay * pay, const guint8 * data, guint size, guint pos)
{
gssize ret = -1;
guint offset;
GST_LOG_OBJECT (pay, "Search for GOB from pos %u", pos);
for (offset = pos / 8; offset < size - 1; offset++) {
if (data[offset] == 0x0) {
gint msb = g_bit_nth_msf (data[offset + 1], 8);
gint lsb = offset > 0 ? g_bit_nth_lsf (data[offset - 1], -1) : 0;
if (lsb == -1)
lsb = 8;
if (msb >= 0 && lsb >= msb) {
ret = offset * 8 - msb;
GST_LOG_OBJECT (pay, "Found GOB start code at bitpos %"
G_GSSIZE_FORMAT " (%02x %02x %02x)", ret,
offset > 0 ? data[offset - 1] : 0, data[offset], data[offset + 1]);
break;
}
}
}
return ret;
}
/* Scans after all GOB start codes and initalizes the GOB structure with start
* and end positions. */
static ParseReturn
gst_rtp_h261_pay_init_gobs (GstRtpH261Pay * pay, Gob * gobs, gint num_gobs,
const guint8 * bits, gint len, guint pos)
{
gint i;
for (i = 0; i < num_gobs; i++) {
gssize gobpos = find_gob (pay, bits, len, pos);
if (gobpos == -1) {
GST_WARNING_OBJECT (pay, "Found only %d of %d GOBs", i, num_gobs);
return PARSE_ERROR;
}
GST_LOG_OBJECT (pay, "Found GOB %d at pos %" G_GSSIZE_FORMAT, i, gobpos);
pos = gobpos + GBSC_LEN;
gobs[i].startpos = gobpos;
if (i > 0)
gobs[i - 1].endpos = gobpos;
}
gobs[num_gobs - 1].endpos = len * 8;
return PARSE_OK;
}
static GstFlowReturn
gst_rtp_h261_pay_fragment_push (GstRtpH261Pay * pay, GstBuffer * buffer,
const guint8 * bits, guint start, guint end,
const Macroblock * last_mb_in_previous_packet, gboolean marker)
{
GstBuffer *outbuf;
guint8 *payload;
GstRtpH261PayHeader *header;
gint nbytes;
const Macroblock *last = last_mb_in_previous_packet;
GstRTPBuffer rtp = GST_RTP_BUFFER_INIT;
nbytes = bitrange_to_bytes (start, end);
outbuf = gst_rtp_buffer_new_allocate (nbytes +
GST_RTP_H261_PAYLOAD_HEADER_LEN, 0, 0);
gst_rtp_buffer_map (outbuf, GST_MAP_WRITE, &rtp);
payload = gst_rtp_buffer_get_payload (&rtp);
header = (GstRtpH261PayHeader *) payload;
memset (header, 0, GST_RTP_H261_PAYLOAD_HEADER_LEN);
header->v = 1;
header->sbit = start & 7;
header->ebit = (8 - (end & 7)) & 7;
if (last != NULL && last->mba != 0 && last->mba != 33) {
/* NOTE: MVD assumes that we're running on 2's complement architecture */
guint mbap = last->mba - 1;
header->gobn = last->gobn;
header->mbap1 = mbap >> 1;
header->mbap2 = mbap & 1;
header->quant = last->quant;
header->hmvd1 = last->mvx >> 3;
header->hmvd2 = last->mvx & 7;
header->vmvd = last->mvy;
}
memcpy (payload + GST_RTP_H261_PAYLOAD_HEADER_LEN,
bits + GST_ROUND_DOWN_8 (start) / 8, nbytes);
GST_BUFFER_TIMESTAMP (outbuf) = pay->timestamp;
gst_rtp_buffer_set_marker (&rtp, marker);
pay->offset = end & 7;
GST_DEBUG_OBJECT (pay,
"Push fragment, bytes %d, sbit %d, ebit %d, gobn %d, mbap %d, marker %d",
nbytes, header->sbit, header->ebit, last != NULL ? last->gobn : 0,
last != NULL ? MAX (last->mba - 1, 0) : 0, marker);
gst_rtp_buffer_unmap (&rtp);
gst_rtp_copy_video_meta (pay, outbuf, buffer);
return gst_rtp_base_payload_push (GST_RTP_BASE_PAYLOAD_CAST (pay), outbuf);
}
static GstFlowReturn
gst_rtp_h261_packetize_and_push (GstRtpH261Pay * pay, GstBuffer * buffer,
const guint8 * bits, gsize len)
{
GstFlowReturn ret = GST_FLOW_OK;
GstBitReader br_;
GstBitReader *br = &br_;
guint max_payload_size =
gst_rtp_buffer_calc_payload_len (GST_RTP_BASE_PAYLOAD_MTU (pay) -
GST_RTP_H261_PAYLOAD_HEADER_LEN, 0, 0);
guint startpos;
gint num_gobs = 0;
Gob gobs[MAX_NUM_GOB];
Gob *gob;
Macroblock last_mb_in_previous_packet = { 0 };
gboolean marker;
ParseReturn result;
gst_bit_reader_init (br, bits, len);
gst_bit_reader_set_pos (br, pay->offset);
startpos = pay->offset;
if (parse_picture_header (pay, br, &num_gobs) < PARSE_OK) {
GST_WARNING_OBJECT (pay, "Failed to parse picture header");
goto beach;
}
if (gst_rtp_h261_pay_init_gobs (pay, gobs, num_gobs, bits, len,
gst_bit_reader_get_pos (br)) < PARSE_OK)
goto beach;
/* Split, create and push packets */
gob = gobs;
marker = FALSE;
while (marker == FALSE && ret == GST_FLOW_OK) {
guint endpos;
/* Check if there is wrap around because of extremely high MTU */
endpos = GST_ROUND_DOWN_8 (startpos) + max_payload_size * 8;
if (endpos < startpos)
endpos = G_MAXUINT;
GST_LOG_OBJECT (pay, "Next packet startpos %u maxpos %u", startpos, endpos);
/* Find the last GOB that does not completely fit in packet */
for (; gob < &gobs[num_gobs - 1]; gob++) {
if (bitrange_to_bytes (startpos, gob->endpos) > max_payload_size) {
GST_LOG_OBJECT (pay, "Split gob (start %u, end %u)",
gob->startpos, gob->endpos);
break;
}
}
if (startpos <= gob->startpos) {
/* Fast-forward until start of GOB */
gst_bit_reader_set_pos (br, gob->startpos);
if (parse_gob_header (pay, br, gob) < PARSE_OK) {
GST_WARNING_OBJECT (pay, "Failed to parse GOB header");
goto beach;
}
gob->last.mba = 0;
gob->last.gobn = gob->gn;
gob->last.quant = gob->gquant;
}
/* Parse MBs to find position where to split. Can only be done on after MB
* or at GOB boundary. */
result = parse_mb_until_pos (pay, br, gob, &endpos);
if (result < PARSE_OK)
goto beach;
marker = result == PARSE_END_OF_FRAME;
ret = gst_rtp_h261_pay_fragment_push (pay, buffer, bits, startpos, endpos,
&last_mb_in_previous_packet, marker);
last_mb_in_previous_packet = gob->last;
if (endpos == gob->endpos)
gob++;
startpos = endpos;
}
beach:
return ret;
}
/* Shift buffer to packetize a continuous stream of bits (not bytes). Some
* payloaders/decoders are very picky about correct sbit/ebit for frames. */
static guint8 *
gst_rtp_h261_pay_shift_buffer (GstRtpH261Pay * pay, const guint8 * data,
gsize size, gint offset, gsize * newsize)
{
/* In order to read variable length codes at the very end of the buffer
* wihout peeking into possibly unallocated data, we pad with extra 0's
* which will generate an invalid code at the end of the buffer. */
guint pad = 4;
gsize allocsize = size + pad;
guint8 *bits = g_malloc (allocsize);
gint i;
if (offset == 0) {
memcpy (bits, data, size);
*newsize = size;
} else if (offset > 0) {
bits[0] = 0;
for (i = 0; i < size; i++) {
bits[i] |= data[i] >> offset;
bits[i + 1] = data[i] << (8 - offset);
}
*newsize = size + 1;
} else {
gint shift = -offset;
for (i = 0; i < size - 1; i++)
bits[i] = (data[i] << shift) | (data[i + 1] >> (8 - shift));
bits[i] = data[i] << shift;
*newsize = size;
}
for (i = *newsize; i < allocsize; i++)
bits[i] = 0;
return bits;
}
static GstFlowReturn
gst_rtp_h261_pay_handle_buffer (GstRTPBasePayload * payload, GstBuffer * buffer)
{
GstFlowReturn ret = GST_FLOW_OK;
GstRtpH261Pay *pay = GST_RTP_H261_PAY (payload);
gsize len;
guint8 *bits;
gint psc_offset, shift;
GstMapInfo map;
GST_DEBUG_OBJECT (pay, "Handle buffer of size %" G_GSIZE_FORMAT,
gst_buffer_get_size (buffer));
pay->timestamp = GST_BUFFER_TIMESTAMP (buffer);
if (!gst_buffer_map (buffer, &map, GST_MAP_READ) || !map.data) {
GST_WARNING_OBJECT (pay, "Failed to map buffer");
return GST_FLOW_ERROR;
}
psc_offset = find_picture_header_offset (map.data, map.size);
if (psc_offset < 0) {
GST_WARNING_OBJECT (pay, "Failed to find picture header offset");
goto beach;
} else {
GST_DEBUG_OBJECT (pay, "Picture header offset: %d", psc_offset);
}
shift = pay->offset - psc_offset;
bits = gst_rtp_h261_pay_shift_buffer (pay, map.data, map.size, shift, &len);
ret = gst_rtp_h261_packetize_and_push (pay, buffer, bits, len);
g_free (bits);
beach:
gst_buffer_unmap (buffer, &map);
gst_buffer_unref (buffer);
return ret;
}
static gboolean
gst_rtp_h261_pay_setcaps (GstRTPBasePayload * payload, GstCaps * caps)
{
gboolean res;
gst_rtp_base_payload_set_options (payload, "video",
payload->pt != GST_RTP_PAYLOAD_H261, "H261", 90000);
res = gst_rtp_base_payload_set_outcaps (payload, NULL);
return res;
}
static void
gst_rtp_h261_pay_init (GstRtpH261Pay * pay)
{
GstRTPBasePayload *payload = GST_RTP_BASE_PAYLOAD (pay);
payload->pt = GST_RTP_PAYLOAD_H261;
pay->offset = 0;
}
static void
gst_rtp_h261_pay_class_init (GstRtpH261PayClass * klass)
{
GstElementClass *element_class;
GstRTPBasePayloadClass *gstrtpbasepayload_class;
element_class = GST_ELEMENT_CLASS (klass);
gstrtpbasepayload_class = GST_RTP_BASE_PAYLOAD_CLASS (klass);
gst_element_class_add_static_pad_template (element_class,
&gst_rtp_h261_pay_src_template);
gst_element_class_add_static_pad_template (element_class,
&gst_rtp_h261_pay_sink_template);
gst_element_class_set_static_metadata (element_class,
"RTP H261 packet payloader", "Codec/Payloader/Network/RTP",
"Payload-encodes H261 video in RTP packets (RFC 4587)",
"Stian Selnes <stian@pexip.com>");
gstrtpbasepayload_class->set_caps = gst_rtp_h261_pay_setcaps;
gstrtpbasepayload_class->handle_buffer = gst_rtp_h261_pay_handle_buffer;
GST_DEBUG_CATEGORY_INIT (rtph261pay_debug, "rtph261pay", 0,
"H261 RTP Payloader");
}
gboolean
gst_rtp_h261_pay_plugin_init (GstPlugin * plugin)
{
return gst_element_register (plugin, "rtph261pay",
GST_RANK_SECONDARY, GST_TYPE_RTP_H261_PAY);
}
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