rtpenc: MP4A-LATM payload support

This is enabled with an AVOption on the RTP muxer. The SDP
generator looks for a latm flag in the rtpflags field.

Signed-off-by: Martin Storsjö <martin@martin.st>

1 files changed, 61 insertions, 0 deletions

diff --git a/libavformat/rtpenc_latm.c b/libavformat/rtpenc_latm.c
new file mode 100644
index 0000000000..aa6e29117f
--- /dev/null
+++ b/libavformat/rtpenc_latm.c
@@ -0,0 +1,61 @@
+/*
+ * RTP Packetization of MPEG-4 Audio (RFC 3016)
+ * Copyright (c) 2011 Juan Carlos Rodriguez <ing.juancarlosrodriguez@hotmail.com>
+ *
+ * This file is part of Libav.
+ *
+ * Libav 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.
+ *
+ * FFmpeg 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 FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "avformat.h"
+#include "rtpenc.h"
+
+void ff_rtp_send_latm(AVFormatContext *s1, const uint8_t *buff, int size)
+{
+    /* MP4A-LATM
+     * The RTP payload format specification is described in RFC 3016
+     * The encoding specifications are provided in ISO/IEC 14496-3 */
+
+    RTPMuxContext *s = s1->priv_data;
+    int header_size;
+    int offset = 0;
+    int len    = 0;
+
+    /* skip ADTS header, if present */
+    if ((s1->streams[0]->codec->extradata_size) == 0) {
+        size -= 7;
+        buff += 7;
+    }
+
+    /* PayloadLengthInfo() */
+    header_size = size/0xFF + 1;
+    memset(s->buf, 0xFF, header_size - 1);
+    s->buf[header_size - 1] = size % 0xFF;
+
+    s->timestamp = s->cur_timestamp;
+
+    /* PayloadMux() */
+    while (size > 0) {
+        len   = FFMIN(size, s->max_payload_size - (!offset ? header_size : 0));
+        size -= len;
+        if (!offset) {
+            memcpy(s->buf + header_size, buff, len);
+            ff_rtp_send_data(s1, s->buf, header_size + len, !size);
+        } else {
+            ff_rtp_send_data(s1, buff + offset, len, !size);
+        }
+        offset += len;
+    }
+}