rtpdec: experimental VP9 depacketizer (draft 0)

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Changelog

@@ -26,6 +26,7 @@ version <next>:
 - RTP parser for loss tolerant payload format for MP3 audio (RFC 5219)
 - RTP parser for AC3 payload format (RFC 4184)
 - palettegen and paletteuse filters
+- VP9 RTP payload format (draft 0) experimental depacketizer
 
 
 version 2.5:

MAINTAINERS

@@ -469,6 +469,7 @@ Muxers/Demuxers:
   rtpdec_h261.*, rtpenc_h261.*          Thomas Volkert
   rtpdec_hevc.*, rtpenc_hevc.*          Thomas Volkert
   rtpdec_asf.*                          Ronald S. Bultje
+  rtpdec_vp9.c                          Thomas Volkert
   rtpenc_mpv.*, rtpenc_aac.*            Martin Storsjo
   rtsp.c                                Luca Barbato
   sbgdec.c                              Nicolas George

libavformat/Makefile

@@ -49,6 +49,7 @@ OBJS-$(CONFIG_RTPDEC)                    += rdt.o                       \
                                             rtpdec_qt.o                 \
                                             rtpdec_svq3.o               \
                                             rtpdec_vp8.o                \
+                                            rtpdec_vp9.o                \
                                             rtpdec_xiph.o               \
                                             srtp.o
 OBJS-$(CONFIG_RTPENC_CHAIN)              += rtpenc_chain.o rtp.o

libavformat/rtpdec.c

@@ -107,6 +107,7 @@ void ff_register_rtp_dynamic_payload_handlers(void)
     ff_register_dynamic_payload_handler(&ff_theora_dynamic_handler);
     ff_register_dynamic_payload_handler(&ff_vorbis_dynamic_handler);
     ff_register_dynamic_payload_handler(&ff_vp8_dynamic_handler);
+    ff_register_dynamic_payload_handler(&ff_vp9_dynamic_handler);
     ff_register_dynamic_payload_handler(&gsm_dynamic_handler);
     ff_register_dynamic_payload_handler(&opus_dynamic_handler);
     ff_register_dynamic_payload_handler(&realmedia_mp3_dynamic_handler);

libavformat/rtpdec_formats.h

@@ -69,5 +69,6 @@ extern RTPDynamicProtocolHandler ff_svq3_dynamic_handler;
 extern RTPDynamicProtocolHandler ff_theora_dynamic_handler;
 extern RTPDynamicProtocolHandler ff_vorbis_dynamic_handler;
 extern RTPDynamicProtocolHandler ff_vp8_dynamic_handler;
+extern RTPDynamicProtocolHandler ff_vp9_dynamic_handler;
 
 #endif /* AVFORMAT_RTPDEC_FORMATS_H */

libavformat/rtpdec_vp9.c

+/*
+ * RTP parser for VP9 payload format (draft version 0) - experimental
+ * Copyright (c) 2015 Thomas Volkert <thomas@homer-conferencing.com>
+ *
+ * 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 "libavcodec/bytestream.h"
+
+#include "rtpdec_formats.h"
+
+#define RTP_VP9_DESC_REQUIRED_SIZE 1
+
+struct PayloadContext {
+    AVIOContext *buf;
+    uint32_t     timestamp;
+};
+
+static av_cold PayloadContext *vp9_new_context(void)
+{
+    return av_mallocz(sizeof(PayloadContext));
+}
+
+static void vp9_free_dyn_buffer(AVIOContext **dyn_buf)
+{
+    uint8_t *ptr_dyn_buffer;
+    avio_close_dyn_buf(*dyn_buf, &ptr_dyn_buffer);
+    av_free(ptr_dyn_buffer);
+    *dyn_buf = NULL;
+}
+
+static av_cold void vp9_free_context(PayloadContext *data)
+{
+    av_free(data);
+}
+
+static av_cold int vp9_init(AVFormatContext *ctx, int st_index,
+                             PayloadContext *data)
+{
+    av_dlog(ctx, "vp9_init() for stream %d\n", st_index);
+    av_log(ctx, AV_LOG_WARNING,
+           "RTP/VP9 support is still experimental\n");
+
+    if (st_index < 0)
+        return 0;
+
+    ctx->streams[st_index]->need_parsing = AVSTREAM_PARSE_FULL;
+
+    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 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) {
+        vp9_free_dyn_buffer(&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;
+
+    /* sanity check for markers: B should always be equal to the RTP M marker */
+    if (last_fragment >> 2 != flags & RTP_FLAG_MARKER) {
+        av_log(ctx, AV_LOG_ERROR, "Invalid combination of B and M marker\n");
+        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");
+            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\n");
+        return AVERROR_PATCHWELCOME;
+    }
+
+    /*
+      decode the scalability update structure (SU)
+
+        spec. is tbd
+     */
+    if (has_su_data) {
+        avpriv_report_missing_feature(ctx, "VP9 scalability update structure data\n");
+        return AVERROR_PATCHWELCOME;
+    }
+
+    /*
+      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,
+    .init             = vp9_init,
+    .alloc            = vp9_new_context,
+    .free             = vp9_free_context,
+    .parse_packet     = vp9_handle_packet
+};