rtpdec: experimental VP9 depacketizer (draft 0)

The code was tested with live555 server.

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

1 files changed, 294 insertions, 0 deletions

diff --git a/libavformat/rtpdec_vp9.c b/libavformat/rtpdec_vp9.c
new file mode 100644
index 0000000000..cae6f5395e
--- /dev/null
+++ b/libavformat/rtpdec_vp9.c
@@ -0,0 +1,294 @@
+/*
+ * RTP parser for VP9 payload format (draft version 0) - experimental
+ * Copyright (c) 2015 Thomas Volkert <thomas@homer-conferencing.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.
+ *
+ * Libav 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 Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/intreadwrite.h"
+
+#include "avio_internal.h"
+#include "rtpdec_formats.h"
+
+#define RTP_VP9_DESC_REQUIRED_SIZE 1
+
+struct PayloadContext {
+    AVIOContext *buf;
+    uint32_t     timestamp;
+};
+
+static av_cold int vp9_init(AVFormatContext *ctx, int st_index,
+                            PayloadContext *data)
+{
+    av_log(ctx, AV_LOG_WARNING,
+           "RTP/VP9 support is still experimental\n");
+
+    return 0;
+}
+
+static int vp9_handle_packet(AVFormatContext *ctx, PayloadContext *rtp_vp9_ctx,
+                             AVStream *st, AVPacket *pkt, uint32_t *timestamp,
+                             const uint8_t *buf, int len, uint16_t seq,
+                             int flags)
+{
+    int has_pic_id, has_layer_idc, has_ref_idc, has_ss_data, has_su_data;
+    av_unused int pic_id = 0, non_key_frame = 0;
+    av_unused int layer_temporal = -1, layer_spatial = -1, layer_quality = -1;
+    int ref_fields = 0, has_ref_field_ext_pic_id = 0;
+    int first_fragment, last_fragment;
+    int rtp_m;
+    int res = 0;
+
+    /* drop data of previous packets in case of non-continuous (lossy) packet stream */
+    if (rtp_vp9_ctx->buf && rtp_vp9_ctx->timestamp != *timestamp)
+        ffio_free_dyn_buf(&rtp_vp9_ctx->buf);
+
+    /* sanity check for size of input packet: 1 byte payload at least */
+    if (len < RTP_VP9_DESC_REQUIRED_SIZE + 1) {
+        av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet, got %d bytes\n", len);
+        return AVERROR_INVALIDDATA;
+    }
+
+    /*
+     *     decode the required VP9 payload descriptor according to section 4.2 of the spec.:
+     *
+     *      0 1 2 3 4 5 6 7
+     *     +-+-+-+-+-+-+-+-+
+     *     |I|L|F|B|E|V|U|-| (REQUIRED)
+     *     +-+-+-+-+-+-+-+-+
+     *
+     *     I: PictureID present
+     *     L: Layer indices present
+     *     F: Reference indices present
+     *     B: Start of VP9 frame
+     *     E: End of picture
+     *     V: Scalability Structure (SS) present
+     *     U: Scalability Structure Update (SU) present
+     */
+    has_pic_id     = !!(buf[0] & 0x80);
+    has_layer_idc  = !!(buf[0] & 0x40);
+    has_ref_idc    = !!(buf[0] & 0x20);
+    first_fragment = !!(buf[0] & 0x10);
+    last_fragment  = !!(buf[0] & 0x08);
+    has_ss_data    = !!(buf[0] & 0x04);
+    has_su_data    = !!(buf[0] & 0x02);
+
+    rtp_m = !!(flags & RTP_FLAG_MARKER);
+
+    /* sanity check for markers: B should always be equal to the RTP M marker */
+    if (last_fragment != rtp_m) {
+        av_log(ctx, AV_LOG_ERROR, "Invalid combination of B and M marker (%d != %d)\n", last_fragment, rtp_m);
+        return AVERROR_INVALIDDATA;
+    }
+
+    /* pass the extensions field */
+    buf += RTP_VP9_DESC_REQUIRED_SIZE;
+    len -= RTP_VP9_DESC_REQUIRED_SIZE;
+
+    /*
+     *         decode the 1-byte/2-byte picture ID:
+     *
+     *          0 1 2 3 4 5 6 7
+     *         +-+-+-+-+-+-+-+-+
+     *   I:    |M|PICTURE ID   | (RECOMMENDED)
+     *         +-+-+-+-+-+-+-+-+
+     *   M:    | EXTENDED PID  | (RECOMMENDED)
+     *         +-+-+-+-+-+-+-+-+
+     *
+     *   M: The most significant bit of the first octet is an extension flag.
+     *   PictureID:  8 or 16 bits including the M bit.
+     */
+    if (has_pic_id) {
+        if (len < 1) {
+            av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
+            return AVERROR_INVALIDDATA;
+        }
+
+        /* check for 1-byte or 2-byte picture index */
+        if (buf[0] & 0x80) {
+            if (len < 2) {
+                av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
+                return AVERROR_INVALIDDATA;
+            }
+            pic_id = AV_RB16(buf) & 0x7fff;
+            buf += 2;
+            len -= 2;
+        } else {
+            pic_id = buf[0] & 0x7f;
+            buf++;
+            len--;
+        }
+    }
+
+    /*
+     *         decode layer indices
+     *
+     *          0 1 2 3 4 5 6 7
+     *         +-+-+-+-+-+-+-+-+
+     *   L:    | T | S | Q | R | (CONDITIONALLY RECOMMENDED)
+     *         +-+-+-+-+-+-+-+-+
+     *
+     *   T, S and Q are 2-bit indices for temporal, spatial, and quality layers.
+     *   If "F" is set in the initial octet, R is 2 bits representing the number
+     *   of reference fields this frame refers to.
+     */
+    if (has_layer_idc) {
+        if (len < 1) {
+            av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
+            return AVERROR_INVALIDDATA;
+        }
+        layer_temporal = buf[0] & 0xC0;
+        layer_spatial  = buf[0] & 0x30;
+        layer_quality  = buf[0] & 0x0C;
+        if (has_ref_idc) {
+            ref_fields = buf[0] & 0x03;
+            if (ref_fields)
+                non_key_frame = 1;
+        }
+        buf++;
+        len--;
+    }
+
+    /*
+     *         decode the reference fields
+     *
+     *          0 1 2 3 4 5 6 7
+     *         +-+-+-+-+-+-+-+-+              -\
+     *   F:    | PID |X| RS| RQ| (OPTIONAL)    .
+     *         +-+-+-+-+-+-+-+-+               . - R times
+     *   X:    | EXTENDED PID  | (OPTIONAL)    .
+     *         +-+-+-+-+-+-+-+-+              -/
+     *
+     *   PID:  The relative Picture ID referred to by this frame.
+     *   RS and RQ:  The spatial and quality layer IDs.
+     *   X: 1 if this layer index has an extended relative Picture ID.
+     */
+    if (has_ref_idc) {
+        while (ref_fields) {
+            if (len < 1) {
+                av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
+                return AVERROR_INVALIDDATA;
+            }
+
+            has_ref_field_ext_pic_id = buf[0] & 0x10;
+
+            /* pass ref. field */
+            if (has_ref_field_ext_pic_id) {
+                if (len < 2) {
+                    av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
+                    return AVERROR_INVALIDDATA;
+                }
+
+                /* ignore ref. data */
+
+                buf += 2;
+                len -= 2;
+            } else {
+
+                /* ignore ref. data */
+
+                buf++;
+                len--;
+            }
+            ref_fields--;
+        }
+    }
+
+    /*
+     *         decode the scalability structure (SS)
+     *
+     *          0 1 2 3 4 5 6 7
+     *         +-+-+-+-+-+-+-+-+
+     *   V:    | PATTERN LENGTH|
+     *         +-+-+-+-+-+-+-+-+                           -\
+     *         | T | S | Q | R | (OPTIONAL)                 .
+     *         +-+-+-+-+-+-+-+-+              -\            .
+     *         | PID |X| RS| RQ| (OPTIONAL)    .            . - PAT. LEN. times
+     *         +-+-+-+-+-+-+-+-+               . - R times  .
+     *   X:    | EXTENDED PID  | (OPTIONAL)    .            .
+     *         +-+-+-+-+-+-+-+-+              -/           -/
+     *
+     *   PID:  The relative Picture ID referred to by this frame.
+     *   RS and RQ:  The spatial and quality layer IDs.
+     *   X: 1 if this layer index has an extended relative Picture ID.
+     */
+    if (has_ss_data) {
+        avpriv_report_missing_feature(ctx, "VP9 scalability structure data");
+        return AVERROR(ENOSYS);
+    }
+
+    /*
+     * decode the scalability update structure (SU)
+     *
+     *  spec. is tbd
+     */
+    if (has_su_data) {
+        avpriv_report_missing_feature(ctx, "VP9 scalability update structure data");
+        return AVERROR(ENOSYS);
+    }
+
+    /*
+     * decode the VP9 payload header
+     *
+     *  spec. is tbd
+     */
+    //XXX: implement when specified
+
+    /* sanity check: 1 byte payload as minimum */
+    if (len < 1) {
+        av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    /* start frame buffering with new dynamic buffer */
+    if (!rtp_vp9_ctx->buf) {
+        /* sanity check: a new frame should have started */
+        if (first_fragment) {
+            res = avio_open_dyn_buf(&rtp_vp9_ctx->buf);
+            if (res < 0)
+                return res;
+            /* update the timestamp in the frame packet with the one from the RTP packet */
+            rtp_vp9_ctx->timestamp = *timestamp;
+        } else {
+            /* frame not started yet, need more packets */
+            return AVERROR(EAGAIN);
+        }
+    }
+
+    /* write the fragment to the dyn. buffer */
+    avio_write(rtp_vp9_ctx->buf, buf, len);
+
+    /* do we need more fragments? */
+    if (!last_fragment)
+        return AVERROR(EAGAIN);
+
+    /* close frame buffering and create resulting A/V packet */
+    res = ff_rtp_finalize_packet(pkt, &rtp_vp9_ctx->buf, st->index);
+    if (res < 0)
+        return res;
+
+    return 0;
+}
+
+RTPDynamicProtocolHandler ff_vp9_dynamic_handler = {
+    .enc_name         = "VP9",
+    .codec_type       = AVMEDIA_TYPE_VIDEO,
+    .codec_id         = AV_CODEC_ID_VP9,
+    .priv_data_size   = sizeof(PayloadContext),
+    .init             = vp9_init,
+    .parse_packet     = vp9_handle_packet
+};