gstreamer/gst/rtp/rtpulpfeccommon.c

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/* GStreamer plugin for forward error correction
* Copyright (C) 2017 Pexip
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Author: Mikhail Fludkov <misha@pexip.com>
*/
#include <string.h>
#include "rtpulpfeccommon.h"
#define MIN_RTP_HEADER_LEN 12
typedef struct
{
#if G_BYTE_ORDER == G_LITTLE_ENDIAN
unsigned int csrc_count:4; /* CSRC count */
unsigned int extension:1; /* header extension flag */
unsigned int padding:1; /* padding flag */
unsigned int version:2; /* protocol version */
unsigned int payload_type:7; /* payload type */
unsigned int marker:1; /* marker bit */
#elif G_BYTE_ORDER == G_BIG_ENDIAN
unsigned int version:2; /* protocol version */
unsigned int padding:1; /* padding flag */
unsigned int extension:1; /* header extension flag */
unsigned int csrc_count:4; /* CSRC count */
unsigned int marker:1; /* marker bit */
unsigned int payload_type:7; /* payload type */
#else
#error "G_BYTE_ORDER should be big or little endian."
#endif
unsigned int seq:16; /* sequence number */
unsigned int timestamp:32; /* timestamp */
unsigned int ssrc:32; /* synchronization source */
guint8 csrclist[4]; /* optional CSRC list, 32 bits each */
} RtpHeader;
static gsize
fec_level_hdr_get_size (gboolean l_bit)
{
return sizeof (RtpUlpFecLevelHeader) - (l_bit ? 0 : 4);
}
static guint64
fec_level_hdr_get_mask (RtpUlpFecLevelHeader const *fec_lvl_hdr, gboolean l_bit)
{
return ((guint64) g_ntohs (fec_lvl_hdr->mask) << 32) |
(l_bit ? g_ntohl (fec_lvl_hdr->mask_continued) : 0);
}
static void
fec_level_hdr_set_mask (RtpUlpFecLevelHeader * fec_lvl_hdr, gboolean l_bit,
guint64 mask)
{
fec_lvl_hdr->mask = g_htons (mask >> 32);
if (l_bit)
fec_lvl_hdr->mask_continued = g_htonl (mask);
}
static guint16
fec_level_hdr_get_protection_len (RtpUlpFecLevelHeader * fec_lvl_hdr)
{
return g_ntohs (fec_lvl_hdr->protection_len);
}
static void
fec_level_hdr_set_protection_len (RtpUlpFecLevelHeader * fec_lvl_hdr,
guint16 len)
{
fec_lvl_hdr->protection_len = g_htons (len);
}
static RtpUlpFecLevelHeader *
fec_hdr_get_level_hdr (RtpUlpFecHeader const *fec_hdr)
{
return (RtpUlpFecLevelHeader *) (fec_hdr + 1);
}
static guint64
fec_hdr_get_mask (RtpUlpFecHeader const *fec_hdr)
{
return fec_level_hdr_get_mask (fec_hdr_get_level_hdr (fec_hdr), fec_hdr->L);
}
static guint16
fec_hdr_get_seq_base (RtpUlpFecHeader const *fec_hdr, gboolean is_ulpfec,
guint16 fec_seq)
{
guint16 seq = g_ntohs (fec_hdr->seq);
if (is_ulpfec)
return seq;
return fec_seq - seq;
}
static guint16
fec_hdr_get_packets_len_recovery (RtpUlpFecHeader const *fec_hdr)
{
return g_htons (fec_hdr->len);
}
static guint32
fec_hdr_get_timestamp_recovery (RtpUlpFecHeader const *fec_hdr)
{
return g_ntohl (fec_hdr->timestamp);
}
static void
_xor_mem (guint8 * restrict dst, const guint8 * restrict src, gsize length)
{
guint i;
for (i = 0; i < (length / sizeof (guint64)); ++i) {
*((guint64 *) dst) ^= *((const guint64 *) src);
dst += sizeof (guint64);
src += sizeof (guint64);
}
for (i = 0; i < (length % sizeof (guint64)); ++i)
dst[i] ^= src[i];
}
guint16
rtp_ulpfec_hdr_get_protection_len (RtpUlpFecHeader const *fec_hdr)
{
return fec_level_hdr_get_protection_len (fec_hdr_get_level_hdr (fec_hdr));
}
RtpUlpFecHeader *
rtp_ulpfec_buffer_get_fechdr (GstRTPBuffer * rtp)
{
return (RtpUlpFecHeader *) gst_rtp_buffer_get_payload (rtp);
}
guint64
rtp_ulpfec_buffer_get_mask (GstRTPBuffer * rtp)
{
return fec_hdr_get_mask (rtp_ulpfec_buffer_get_fechdr (rtp));
}
guint16
rtp_ulpfec_buffer_get_seq_base (GstRTPBuffer * rtp)
{
return g_ntohs (rtp_ulpfec_buffer_get_fechdr (rtp)->seq);
}
guint
rtp_ulpfec_get_headers_len (gboolean fec_mask_long)
{
return sizeof (RtpUlpFecHeader) + fec_level_hdr_get_size (fec_mask_long);
}
#define ONE_64BIT G_GUINT64_CONSTANT(1)
guint64
rtp_ulpfec_packet_mask_from_seqnum (guint16 seq,
guint16 fec_seq_base, gboolean fec_mask_long)
{
gint seq_delta = gst_rtp_buffer_compare_seqnum (fec_seq_base, seq);
if (seq_delta >= 0
&& seq_delta <= RTP_ULPFEC_SEQ_BASE_OFFSET_MAX (fec_mask_long)) {
return ONE_64BIT << (RTP_ULPFEC_SEQ_BASE_OFFSET_MAX (TRUE) - seq_delta);
}
return 0;
}
gboolean
rtp_ulpfec_mask_is_long (guint64 mask)
{
return (mask & 0xffffffff) ? TRUE : FALSE;
}
gboolean
rtp_ulpfec_buffer_is_valid (GstRTPBuffer * rtp)
{
guint payload_len = gst_rtp_buffer_get_payload_len (rtp);
RtpUlpFecHeader *fec_hdr;
guint fec_hdrs_len;
guint fec_packet_len;
if (payload_len < sizeof (RtpUlpFecHeader))
goto toosmall;
fec_hdr = rtp_ulpfec_buffer_get_fechdr (rtp);
if (fec_hdr->E)
goto invalidcontent;
fec_hdrs_len = rtp_ulpfec_get_headers_len (fec_hdr->L);
if (payload_len < fec_hdrs_len)
goto toosmall;
fec_packet_len = fec_hdrs_len + rtp_ulpfec_hdr_get_protection_len (fec_hdr);
if (fec_packet_len != payload_len)
goto lengthmismatch;
return TRUE;
toosmall:
GST_WARNING ("FEC packet too small");
return FALSE;
lengthmismatch:
GST_WARNING ("invalid FEC packet (declared length %u, real length %u)",
fec_packet_len, payload_len);
return FALSE;
invalidcontent:
GST_WARNING ("FEC Header contains invalid fields: %u", fec_hdr->E);
return FALSE;
}
void
rtp_buffer_to_ulpfec_bitstring (GstRTPBuffer * rtp, GArray * dst_arr,
gboolean fec_buffer, gboolean fec_mask_long)
{
if (G_UNLIKELY (fec_buffer)) {
guint payload_len = gst_rtp_buffer_get_payload_len (rtp);
g_array_set_size (dst_arr, MAX (payload_len, dst_arr->len));
memcpy (dst_arr->data, gst_rtp_buffer_get_payload (rtp), payload_len);
} else {
const guint8 *src = rtp->data[0];
guint len = gst_rtp_buffer_get_packet_len (rtp) - MIN_RTP_HEADER_LEN;
guint dst_offset = rtp_ulpfec_get_headers_len (fec_mask_long);
guint src_offset = MIN_RTP_HEADER_LEN;
guint8 *dst;
g_array_set_size (dst_arr, MAX (dst_offset + len, dst_arr->len));
dst = (guint8 *) dst_arr->data;
*((guint64 *) dst) ^= *((const guint64 *) src);
((RtpUlpFecHeader *) dst)->len ^= g_htons (len);
_xor_mem (dst + dst_offset, src + src_offset, len);
}
}
GstBuffer *
rtp_ulpfec_bitstring_to_media_rtp_buffer (GArray * arr,
gboolean fec_mask_long, guint32 ssrc, guint16 seq)
{
guint fec_hdrs_len = rtp_ulpfec_get_headers_len (fec_mask_long);
guint payload_len =
fec_hdr_get_packets_len_recovery ((RtpUlpFecHeader *) arr->data);
GstMapInfo ret_info = GST_MAP_INFO_INIT;
GstMemory *ret_mem;
GstBuffer *ret;
if (payload_len > arr->len - fec_hdrs_len)
return NULL; // Not enough data
ret_mem = gst_allocator_alloc (NULL, MIN_RTP_HEADER_LEN + payload_len, NULL);
gst_memory_map (ret_mem, &ret_info, GST_MAP_READWRITE);
/* Filling 12 bytes of RTP header */
*((guint64 *) ret_info.data) = *((guint64 *) arr->data);
((RtpHeader *) ret_info.data)->version = 2;
((RtpHeader *) ret_info.data)->seq = g_htons (seq);
((RtpHeader *) ret_info.data)->ssrc = g_htonl (ssrc);
/* Filling payload */
memcpy (ret_info.data + MIN_RTP_HEADER_LEN,
arr->data + fec_hdrs_len, payload_len);
gst_memory_unmap (ret_mem, &ret_info);
ret = gst_buffer_new ();
gst_buffer_append_memory (ret, ret_mem);
return ret;
}
GstBuffer *
rtp_ulpfec_bitstring_to_fec_rtp_buffer (GArray * arr,
guint16 seq_base, gboolean fec_mask_long, guint64 fec_mask,
gboolean marker, guint8 pt, guint16 seq, guint32 timestamp, guint32 ssrc)
{
GstRTPBuffer rtp = GST_RTP_BUFFER_INIT;
GstBuffer *ret;
/* Filling FEC headers */
{
RtpUlpFecHeader *hdr = (RtpUlpFecHeader *) arr->data;
RtpUlpFecLevelHeader *lvlhdr;
hdr->E = 0;
hdr->L = fec_mask_long;
hdr->seq = g_htons (seq_base);
lvlhdr = fec_hdr_get_level_hdr (hdr);
fec_level_hdr_set_protection_len (lvlhdr,
arr->len - rtp_ulpfec_get_headers_len (fec_mask_long));
fec_level_hdr_set_mask (lvlhdr, fec_mask_long, fec_mask);
}
/* Filling RTP header, copying payload */
ret = gst_rtp_buffer_new_allocate (arr->len, 0, 0);
if (!gst_rtp_buffer_map (ret, GST_MAP_READWRITE, &rtp))
g_assert_not_reached ();
gst_rtp_buffer_set_marker (&rtp, marker);
gst_rtp_buffer_set_payload_type (&rtp, pt);
gst_rtp_buffer_set_seq (&rtp, seq);
gst_rtp_buffer_set_timestamp (&rtp, timestamp);
gst_rtp_buffer_set_ssrc (&rtp, ssrc);
memcpy (gst_rtp_buffer_get_payload (&rtp), arr->data, arr->len);
gst_rtp_buffer_unmap (&rtp);
return ret;
}
/**
* rtp_ulpfec_map_info_map:
* @buffer: (transfer: full) #GstBuffer
* @info: #RtpUlpFecMapInfo
*
* Maps the contents of @buffer into @info. If @buffer made of many #GstMemory
* objects, merges them together to create a new buffer made of single
* continious #GstMemory.
*
* Returns: %TRUE if @buffer could be mapped
**/
gboolean
rtp_ulpfec_map_info_map (GstBuffer * buffer, RtpUlpFecMapInfo * info)
{
/* We need to make sure we are working with continious memory chunk.
* If not merge all memories together */
if (gst_buffer_n_memory (buffer) > 1) {
GstBuffer *new_buffer = gst_buffer_new ();
GstMemory *mem = gst_buffer_get_all_memory (buffer);
gst_buffer_append_memory (new_buffer, mem);
/* We supposed to own the old buffer, but we don't use it here, so unref */
gst_buffer_unref (buffer);
buffer = new_buffer;
}
if (!gst_rtp_buffer_map (buffer,
GST_MAP_READ | GST_RTP_BUFFER_MAP_FLAG_SKIP_PADDING, &info->rtp)) {
/* info->rtp.buffer = NULL is an indication for rtp_ulpfec_map_info_unmap()
* that mapping has failed */
g_assert (NULL == info->rtp.buffer);
gst_buffer_unref (buffer);
return FALSE;
}
return TRUE;
}
/**
* rtp_ulpfec_map_info_unmap:
* @info: #RtpUlpFecMapInfo
*
* Unmap @info previously mapped with rtp_ulpfec_map_info_map() and unrefs the
* buffer. For convinience can even be called even if rtp_ulpfec_map_info_map
* returned FALSE
**/
void
rtp_ulpfec_map_info_unmap (RtpUlpFecMapInfo * info)
{
GstBuffer *buffer = info->rtp.buffer;
if (buffer) {
gst_rtp_buffer_unmap (&info->rtp);
gst_buffer_unref (buffer);
}
}
#ifndef GST_DISABLE_GST_DEBUG
void
rtp_ulpfec_log_rtppacket (GstDebugCategory * cat, GstDebugLevel level,
gpointer object, const gchar * name, GstRTPBuffer * rtp)
{
guint seq;
guint ssrc;
guint timestamp;
guint pt;
if (level > gst_debug_category_get_threshold (cat))
return;
seq = gst_rtp_buffer_get_seq (rtp);
ssrc = gst_rtp_buffer_get_ssrc (rtp);
timestamp = gst_rtp_buffer_get_timestamp (rtp);
pt = gst_rtp_buffer_get_payload_type (rtp);
GST_CAT_LEVEL_LOG (cat, level, object,
"%-22s: [%c%c%c%c] ssrc=0x%08x pt=%u tstamp=%u seq=%u size=%u(%u,%u)",
name,
gst_rtp_buffer_get_marker (rtp) ? 'M' : ' ',
gst_rtp_buffer_get_extension (rtp) ? 'X' : ' ',
gst_rtp_buffer_get_padding (rtp) ? 'P' : ' ',
gst_rtp_buffer_get_csrc_count (rtp) > 0 ? 'C' : ' ',
ssrc, pt, timestamp, seq,
gst_rtp_buffer_get_packet_len (rtp),
gst_rtp_buffer_get_packet_len (rtp) - MIN_RTP_HEADER_LEN,
gst_rtp_buffer_get_payload_len (rtp));
}
#endif /* GST_DISABLE_GST_DEBUG */
#ifndef GST_DISABLE_GST_DEBUG
void
rtp_ulpfec_log_fec_packet (GstDebugCategory * cat, GstDebugLevel level,
gpointer object, GstRTPBuffer * fecrtp)
{
RtpUlpFecHeader *fec_hdr;
RtpUlpFecLevelHeader *fec_level_hdr;
if (level > gst_debug_category_get_threshold (cat))
return;
fec_hdr = gst_rtp_buffer_get_payload (fecrtp);
GST_CAT_LEVEL_LOG (cat, level, object,
"%-22s: [%c%c%c%c%c%c] pt=%u tstamp=%u seq=%u recovery_len=%u",
"fec header",
fec_hdr->E ? 'E' : ' ',
fec_hdr->L ? 'L' : ' ',
fec_hdr->P ? 'P' : ' ',
fec_hdr->X ? 'X' : ' ',
fec_hdr->CC ? 'C' : ' ',
fec_hdr->M ? 'M' : ' ',
fec_hdr->pt,
fec_hdr_get_timestamp_recovery (fec_hdr),
fec_hdr_get_seq_base (fec_hdr, TRUE,
gst_rtp_buffer_get_seq (fecrtp)),
fec_hdr_get_packets_len_recovery (fec_hdr));
fec_level_hdr = fec_hdr_get_level_hdr (fec_hdr);
GST_CAT_LEVEL_LOG (cat, level, object,
"%-22s: protection_len=%u mask=0x%012" G_GINT64_MODIFIER "x",
"fec level header",
g_ntohs (fec_level_hdr->protection_len),
fec_level_hdr_get_mask (fec_level_hdr, fec_hdr->L));
}
#endif /* GST_DISABLE_GST_DEBUG */