Add initial support for RTP hinting in the mov muxer

backport r23164 by mstorsjo


Originally committed as revision 23237 to svn://svn.ffmpeg.org/ffmpeg/branches/0.6

1 files changed, 292 insertions, 0 deletions

diff --git a/libavformat/movenchint.c b/libavformat/movenchint.c
new file mode 100644
index 0000000000..e830b741a8
--- /dev/null
+++ b/libavformat/movenchint.c
@@ -0,0 +1,292 @@
+/*
+ * MOV, 3GP, MP4 muxer RTP hinting
+ * Copyright (c) 2010 Martin Storsjo
+ *
+ * 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
+ */
+
+#include "movenc.h"
+#include "libavutil/intreadwrite.h"
+
+int ff_mov_init_hinting(AVFormatContext *s, int index, int src_index)
+{
+    MOVMuxContext *mov  = s->priv_data;
+    MOVTrack *track     = &mov->tracks[index];
+    MOVTrack *src_track = &mov->tracks[src_index];
+    AVStream *src_st    = s->streams[src_index];
+    int ret = AVERROR(ENOMEM);
+    AVOutputFormat *rtp_format = av_guess_format("rtp", NULL, NULL);
+
+    track->tag = MKTAG('r','t','p',' ');
+    track->src_track = src_index;
+
+    if (!rtp_format) {
+        ret = AVERROR(ENOENT);
+        goto fail;
+    }
+
+    track->enc = avcodec_alloc_context();
+    if (!track->enc)
+        goto fail;
+    track->enc->codec_type = AVMEDIA_TYPE_DATA;
+    track->enc->codec_tag  = track->tag;
+
+    track->rtp_ctx = avformat_alloc_context();
+    if (!track->rtp_ctx)
+        goto fail;
+    track->rtp_ctx->oformat = rtp_format;
+    if (!av_new_stream(track->rtp_ctx, 0))
+        goto fail;
+
+    /* Copy stream parameters */
+    track->rtp_ctx->streams[0]->sample_aspect_ratio =
+                        src_st->sample_aspect_ratio;
+
+    /* Remove the allocated codec context, link to the original one
+     * instead, to give the rtp muxer access to codec parameters. */
+    av_free(track->rtp_ctx->streams[0]->codec);
+    track->rtp_ctx->streams[0]->codec = src_st->codec;
+
+    if ((ret = url_open_dyn_packet_buf(&track->rtp_ctx->pb,
+                                       RTP_MAX_PACKET_SIZE)) < 0)
+        goto fail;
+    ret = av_write_header(track->rtp_ctx);
+    if (ret)
+        goto fail;
+
+    /* Copy the RTP AVStream timebase back to the hint AVStream */
+    track->timescale = track->rtp_ctx->streams[0]->time_base.den;
+
+    /* Mark the hinted track that packets written to it should be
+     * sent to this track for hinting. */
+    src_track->hint_track = index;
+    return 0;
+fail:
+    av_log(s, AV_LOG_WARNING,
+           "Unable to initialize hinting of stream %d\n", src_index);
+    if (track->rtp_ctx && track->rtp_ctx->pb) {
+        uint8_t *buf;
+        url_close_dyn_buf(track->rtp_ctx->pb, &buf);
+        av_free(buf);
+    }
+    if (track->rtp_ctx && track->rtp_ctx->streams[0]) {
+        av_metadata_free(&track->rtp_ctx->streams[0]->metadata);
+        av_free(track->rtp_ctx->streams[0]);
+    }
+    if (track->rtp_ctx) {
+        av_metadata_free(&track->rtp_ctx->metadata);
+        av_free(track->rtp_ctx->priv_data);
+        av_freep(&track->rtp_ctx);
+    }
+    av_freep(&track->enc);
+    /* Set a default timescale, to avoid crashes in dump_format */
+    track->timescale = 90000;
+    return ret;
+}
+
+static void output_immediate(const uint8_t *data, int size,
+                             ByteIOContext *out, int *entries)
+{
+    while (size > 0) {
+        int len = size;
+        if (len > 14)
+            len = 14;
+        put_byte(out, 1); /* immediate constructor */
+        put_byte(out, len); /* amount of valid data */
+        put_buffer(out, data, len);
+        data += len;
+        size -= len;
+
+        for (; len < 14; len++)
+            put_byte(out, 0);
+
+        (*entries)++;
+    }
+}
+
+static void describe_payload(const uint8_t *data, int size,
+                             ByteIOContext *out, int *entries)
+{
+    /* Describe the payload using different constructors */
+    output_immediate(data, size, out, entries);
+}
+
+/**
+ * Write an RTP hint (that may contain one or more RTP packets)
+ * for the packets in data. data contains one or more packets with a
+ * BE32 size header.
+ *
+ * @param out buffer where the hints are written
+ * @param data buffer containing RTP packets
+ * @param size the size of the data buffer
+ * @param trk the MOVTrack for the hint track
+ * @param pts pointer where the timestamp for the written RTP hint is stored
+ * @return the number of RTP packets in the written hint
+ */
+static int write_hint_packets(ByteIOContext *out, const uint8_t *data,
+                              int size, MOVTrack *trk, int64_t *pts)
+{
+    int64_t curpos;
+    int64_t count_pos, entries_pos;
+    int count = 0, entries;
+
+    count_pos = url_ftell(out);
+    /* RTPsample header */
+    put_be16(out, 0); /* packet count */
+    put_be16(out, 0); /* reserved */
+
+    while (size > 4) {
+        uint32_t packet_len = AV_RB32(data);
+        uint16_t seq;
+        uint32_t ts;
+
+        data += 4;
+        size -= 4;
+        if (packet_len > size || packet_len <= 12)
+            break;
+        if (data[1] >= 200 && data[1] <= 204) {
+            /* RTCP packet, just skip */
+            data += packet_len;
+            size -= packet_len;
+            continue;
+        }
+
+        if (packet_len > trk->max_packet_size)
+            trk->max_packet_size = packet_len;
+
+        seq = AV_RB16(&data[2]);
+        ts = AV_RB32(&data[4]);
+
+        if (trk->prev_rtp_ts == 0)
+            trk->prev_rtp_ts = ts;
+        /* Unwrap the 32-bit RTP timestamp that wraps around often
+         * into a not (as often) wrapping 64-bit timestamp. */
+        trk->cur_rtp_ts_unwrapped += (int32_t) (ts - trk->prev_rtp_ts);
+        trk->prev_rtp_ts = ts;
+        if (*pts == AV_NOPTS_VALUE)
+            *pts = trk->cur_rtp_ts_unwrapped;
+
+        count++;
+        /* RTPpacket header */
+        put_be32(out, 0); /* relative_time */
+        put_buffer(out, data, 2); /* RTP header */
+        put_be16(out, seq); /* RTPsequenceseed */
+        put_be16(out, 0); /* reserved + flags */
+        entries_pos = url_ftell(out);
+        put_be16(out, 0); /* entry count */
+
+        data += 12;
+        size -= 12;
+        packet_len -= 12;
+
+        entries = 0;
+        /* Write one or more constructors describing the payload data */
+        describe_payload(data, packet_len, out, &entries);
+        data += packet_len;
+        size -= packet_len;
+
+        curpos = url_ftell(out);
+        url_fseek(out, entries_pos, SEEK_SET);
+        put_be16(out, entries);
+        url_fseek(out, curpos, SEEK_SET);
+    }
+
+    curpos = url_ftell(out);
+    url_fseek(out, count_pos, SEEK_SET);
+    put_be16(out, count);
+    url_fseek(out, curpos, SEEK_SET);
+    return count;
+}
+
+int ff_mov_add_hinted_packet(AVFormatContext *s, AVPacket *pkt,
+                             int track_index, int sample)
+{
+    MOVMuxContext *mov = s->priv_data;
+    MOVTrack *trk = &mov->tracks[track_index];
+    AVFormatContext *rtp_ctx = trk->rtp_ctx;
+    uint8_t *buf = NULL;
+    int size;
+    ByteIOContext *hintbuf = NULL;
+    AVPacket hint_pkt;
+    AVPacket local_pkt;
+    int ret = 0, count;
+
+    if (!rtp_ctx)
+        return AVERROR(ENOENT);
+    if (!rtp_ctx->pb)
+        return AVERROR(ENOMEM);
+
+    /* Feed the packet to the RTP muxer */
+    local_pkt = *pkt;
+    local_pkt.stream_index = 0;
+    local_pkt.pts = av_rescale_q(pkt->pts,
+        s->streams[pkt->stream_index]->time_base,
+        rtp_ctx->streams[0]->time_base);
+    local_pkt.dts = av_rescale_q(pkt->dts,
+        s->streams[pkt->stream_index]->time_base,
+        rtp_ctx->streams[0]->time_base);
+    av_write_frame(rtp_ctx, &local_pkt);
+
+    /* Fetch the output from the RTP muxer, open a new output buffer
+     * for next time. */
+    size = url_close_dyn_buf(rtp_ctx->pb, &buf);
+    if ((ret = url_open_dyn_packet_buf(&rtp_ctx->pb,
+                                       RTP_MAX_PACKET_SIZE)) < 0)
+        goto done;
+
+    if (size <= 0)
+        goto done;
+
+    /* Open a buffer for writing the hint */
+    if ((ret = url_open_dyn_buf(&hintbuf)) < 0)
+        goto done;
+    av_init_packet(&hint_pkt);
+    count = write_hint_packets(hintbuf, buf, size, trk, &hint_pkt.dts);
+    av_freep(&buf);
+
+    /* Write the hint data into the hint track */
+    hint_pkt.size = size = url_close_dyn_buf(hintbuf, &buf);
+    hint_pkt.data = buf;
+    hint_pkt.pts  = hint_pkt.dts;
+    hint_pkt.stream_index = track_index;
+    if (pkt->flags & AV_PKT_FLAG_KEY)
+        hint_pkt.flags |= AV_PKT_FLAG_KEY;
+    if (count > 0)
+        ff_mov_write_packet(s, &hint_pkt);
+done:
+    av_free(buf);
+    return ret;
+}
+
+void ff_mov_close_hinting(MOVTrack *track) {
+    AVFormatContext* rtp_ctx = track->rtp_ctx;
+    uint8_t *ptr;
+
+    av_freep(&track->enc);
+    if (!rtp_ctx)
+        return;
+    if (rtp_ctx->pb) {
+        av_write_trailer(rtp_ctx);
+        url_close_dyn_buf(rtp_ctx->pb, &ptr);
+        av_free(ptr);
+    }
+    av_metadata_free(&rtp_ctx->streams[0]->metadata);
+    av_metadata_free(&rtp_ctx->metadata);
+    av_free(rtp_ctx->streams[0]);
+    av_freep(&rtp_ctx);
+}
+