Add RTP depacketization of VP8

Patch by Josh Allmann, joshua dot allmann at gmail

Originally committed as revision 24798 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 153 insertions, 0 deletions

diff --git a/libavformat/rtpdec_vp8.c b/libavformat/rtpdec_vp8.c
new file mode 100644
index 0000000000..8de89ff152
--- /dev/null
+++ b/libavformat/rtpdec_vp8.c
@@ -0,0 +1,153 @@
+/*
+ * RTP VP8 Depacketizer
+ * Copyright (c) 2010 Josh Allmann
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg 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
+ */
+
+/**
+ * @file
+ * @brief RTP support for the VP8 payload
+ * @author Josh Allmann <joshua.allmann@gmail.com>
+ * ( http://www.webmproject.org/code/specs/rtp/ )
+ */
+
+#include "libavcodec/bytestream.h"
+
+#include "rtpdec_formats.h"
+
+struct PayloadContext {
+    ByteIOContext *data;
+    uint32_t       timestamp;
+    int is_keyframe;
+};
+
+static void prepare_packet(AVPacket *pkt, PayloadContext *vp8, int stream)
+{
+    av_init_packet(pkt);
+    pkt->stream_index = stream;
+    pkt->flags        = vp8->is_keyframe ? AV_PKT_FLAG_KEY : 0;
+    pkt->size         = url_close_dyn_buf(vp8->data, &pkt->data);
+    pkt->destruct     = av_destruct_packet;
+    vp8->data         = NULL;
+}
+
+static int vp8_handle_packet(AVFormatContext *ctx,
+                             PayloadContext *vp8,
+                             AVStream *st,
+                             AVPacket *pkt,
+                             uint32_t *timestamp,
+                             const uint8_t *buf,
+                             int len, int flags)
+{
+    int start_packet, end_packet, has_au, ret = AVERROR(EAGAIN);
+
+    if (!buf) {
+        // only called when vp8_handle_packet returns 1
+        if (!vp8->data) {
+            av_log(ctx, AV_LOG_ERROR, "Invalid VP8 data passed\n");
+            return AVERROR_INVALIDDATA;
+        }
+        prepare_packet(pkt, vp8, st->index);
+        *timestamp = vp8->timestamp;
+        return 0;
+    }
+
+    start_packet = *buf & 1;
+    end_packet   = flags & RTP_FLAG_MARKER;
+    has_au       = *buf & 2;
+    buf++;
+    len--;
+
+    if (start_packet) {
+        int res;
+        uint32_t ts = *timestamp;
+        if (vp8->data) {
+            // missing end marker; return old frame anyway. untested
+            prepare_packet(pkt, vp8, st->index);
+            *timestamp = vp8->timestamp; // reset timestamp from old frame
+
+            // if current frame fits into one rtp packet, need to hold
+            // that for the next av_get_packet call
+            ret = end_packet ? 1 : 0;
+        }
+        if ((res = url_open_dyn_buf(&vp8->data)) < 0)
+            return res;
+        vp8->is_keyframe = *buf & 1;
+        vp8->timestamp   = ts;
+     }
+
+    if (!vp8->data || vp8->timestamp != *timestamp && ret == AVERROR(EAGAIN)) {
+        av_log(ctx, AV_LOG_WARNING,
+               "Received no start marker; dropping frame\n");
+        return AVERROR(EAGAIN);
+    }
+
+    // cycle through VP8AU headers if needed
+    // not tested with actual VP8AUs
+    while (len) {
+        int au_len = len;
+        if (has_au && len > 2) {
+            au_len = AV_RB16(buf);
+            buf += 2;
+            len -= 2;
+            if (buf + au_len > buf + len) {
+                av_log(ctx, AV_LOG_ERROR, "Invalid VP8AU length\n");
+                return AVERROR_INVALIDDATA;
+            }
+        }
+
+        put_buffer(vp8->data, buf, au_len);
+        buf += au_len;
+        len -= au_len;
+    }
+
+    if (ret != AVERROR(EAGAIN)) // did we miss a end marker?
+        return ret;
+
+    if (end_packet) {
+        prepare_packet(pkt, vp8, st->index);
+        return 0;
+    }
+
+    return AVERROR(EAGAIN);
+}
+
+static PayloadContext *vp8_new_context(void)
+{
+    av_log(NULL, AV_LOG_WARNING, "RTP VP8 payload is still experimental\n");
+    return av_mallocz(sizeof(PayloadContext));
+}
+
+static void vp8_free_context(PayloadContext *vp8)
+{
+    if (vp8->data) {
+        uint8_t *tmp;
+        url_close_dyn_buf(vp8->data, &tmp);
+        av_free(tmp);
+    }
+    av_free(vp8);
+}
+
+RTPDynamicProtocolHandler ff_vp8_dynamic_handler = {
+    .enc_name       = "VP8",
+    .codec_type     = AVMEDIA_TYPE_VIDEO,
+    .codec_id       = CODEC_ID_VP8,
+    .open           = vp8_new_context,
+    .close          = vp8_free_context,
+    .parse_packet   = vp8_handle_packet,
+};