yading@11: /*
yading@11:  * RTP H.263 Depacketizer, RFC 2190
yading@11:  * Copyright (c) 2012 Martin Storsjo
yading@11:  * Based on the GStreamer H.263 Depayloder:
yading@11:  * Copyright 2005 Wim Taymans
yading@11:  * Copyright 2007 Edward Hervey
yading@11:  * Copyright 2007 Nokia Corporation
yading@11:  * Copyright 2007 Collabora Ltd, Philippe Kalaf
yading@11:  * Copyright 2010 Mark Nauwelaerts
yading@11:  *
yading@11:  * This file is part of Libav.
yading@11:  *
yading@11:  * Libav is free software; you can redistribute it and/or
yading@11:  * modify it under the terms of the GNU Lesser General Public
yading@11:  * License as published by the Free Software Foundation; either
yading@11:  * version 2.1 of the License, or (at your option) any later version.
yading@11:  *
yading@11:  * Libav is distributed in the hope that it will be useful,
yading@11:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@11:  * Lesser General Public License for more details.
yading@11:  *
yading@11:  * You should have received a copy of the GNU Lesser General Public
yading@11:  * License along with Libav; if not, write to the Free Software
yading@11:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@11:  */
yading@11: 
yading@11: #include "avformat.h"
yading@11: #include "rtpdec_formats.h"
yading@11: #include "libavutil/intreadwrite.h"
yading@11: #include "libavcodec/get_bits.h"
yading@11: 
yading@11: struct PayloadContext {
yading@11:     AVIOContext *buf;
yading@11:     uint8_t      endbyte;
yading@11:     int          endbyte_bits;
yading@11:     uint32_t     timestamp;
yading@11:     int          newformat;
yading@11: };
yading@11: 
yading@11: static PayloadContext *h263_new_context(void)
yading@11: {
yading@11:     return av_mallocz(sizeof(PayloadContext));
yading@11: }
yading@11: 
yading@11: static void h263_free_context(PayloadContext *data)
yading@11: {
yading@11:     if (!data)
yading@11:         return;
yading@11:     if (data->buf) {
yading@11:         uint8_t *p;
yading@11:         avio_close_dyn_buf(data->buf, &p);
yading@11:         av_free(p);
yading@11:     }
yading@11:     av_free(data);
yading@11: }
yading@11: 
yading@11: static int h263_init(AVFormatContext *ctx, int st_index, PayloadContext *data)
yading@11: {
yading@11:     if (st_index < 0)
yading@11:         return 0;
yading@11:     ctx->streams[st_index]->need_parsing = AVSTREAM_PARSE_FULL;
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: static int h263_handle_packet(AVFormatContext *ctx, PayloadContext *data,
yading@11:                               AVStream *st, AVPacket *pkt, uint32_t *timestamp,
yading@11:                               const uint8_t *buf, int len, uint16_t seq,
yading@11:                               int flags)
yading@11: {
yading@11:     /* Corresponding to header fields in the RFC */
yading@11:     int f, p, i, sbit, ebit, src, r;
yading@11:     int header_size, ret;
yading@11: 
yading@11:     if (data->newformat)
yading@11:         return ff_h263_handle_packet(ctx, data, st, pkt, timestamp, buf, len,
yading@11:                                      seq, flags);
yading@11: 
yading@11:     if (data->buf && data->timestamp != *timestamp) {
yading@11:         /* Dropping old buffered, unfinished data */
yading@11:         uint8_t *p;
yading@11:         avio_close_dyn_buf(data->buf, &p);
yading@11:         av_free(p);
yading@11:         data->buf = NULL;
yading@11:     }
yading@11: 
yading@11:     if (len < 4) {
yading@11:         av_log(ctx, AV_LOG_ERROR, "Too short H.263 RTP packet: %d\n", len);
yading@11:         return AVERROR_INVALIDDATA;
yading@11:     }
yading@11: 
yading@11:     f = buf[0] & 0x80;
yading@11:     p = buf[0] & 0x40;
yading@11:     if (!f) {
yading@11:         /* Mode A */
yading@11:         header_size = 4;
yading@11:         i = buf[1] & 0x10;
yading@11:         r = ((buf[1] & 0x01) << 3) | ((buf[2] & 0xe0) >> 5);
yading@11:     } else if (!p) {
yading@11:         /* Mode B */
yading@11:         header_size = 8;
yading@11:         if (len < header_size) {
yading@11:             av_log(ctx, AV_LOG_ERROR,
yading@11:                    "Too short H.263 RTP packet: %d bytes, %d header bytes\n",
yading@11:                    len, header_size);
yading@11:             return AVERROR_INVALIDDATA;
yading@11:         }
yading@11:         r = buf[3] & 0x03;
yading@11:         i = buf[4] & 0x80;
yading@11:     } else {
yading@11:         /* Mode C */
yading@11:         header_size = 12;
yading@11:         if (len < header_size) {
yading@11:             av_log(ctx, AV_LOG_ERROR,
yading@11:                    "Too short H.263 RTP packet: %d bytes, %d header bytes\n",
yading@11:                    len, header_size);
yading@11:             return AVERROR_INVALIDDATA;
yading@11:         }
yading@11:         r = buf[3] & 0x03;
yading@11:         i = buf[4] & 0x80;
yading@11:     }
yading@11:     sbit = (buf[0] >> 3) & 0x7;
yading@11:     ebit =  buf[0]       & 0x7;
yading@11:     src  = (buf[1] & 0xe0) >> 5;
yading@11:     if (!(buf[0] & 0xf8)) { /* Reserved bits in RFC 2429/4629 are zero */
yading@11:         if ((src == 0 || src >= 6) && r) {
yading@11:             /* Invalid src for this format, and bits that should be zero
yading@11:              * according to RFC 2190 aren't zero. */
yading@11:             av_log(ctx, AV_LOG_WARNING,
yading@11:                    "Interpreting H263 RTP data as RFC 2429/4629 even though "
yading@11:                    "signalled with a static payload type.\n");
yading@11:             data->newformat = 1;
yading@11:             return ff_h263_handle_packet(ctx, data, st, pkt, timestamp, buf,
yading@11:                                          len, seq, flags);
yading@11:         }
yading@11:     }
yading@11: 
yading@11:     buf += header_size;
yading@11:     len -= header_size;
yading@11: 
yading@11:     if (!data->buf) {
yading@11:         /* Check the picture start code, only start buffering a new frame
yading@11:          * if this is correct */
yading@11:         if (len > 4 && AV_RB32(buf) >> 10 == 0x20) {
yading@11:             ret = avio_open_dyn_buf(&data->buf);
yading@11:             if (ret < 0)
yading@11:                 return ret;
yading@11:             data->timestamp = *timestamp;
yading@11:         } else {
yading@11:             /* Frame not started yet, skipping */
yading@11:             return AVERROR(EAGAIN);
yading@11:         }
yading@11:     }
yading@11: 
yading@11:     if (data->endbyte_bits || sbit) {
yading@11:         if (data->endbyte_bits == sbit) {
yading@11:             data->endbyte |= buf[0] & (0xff >> sbit);
yading@11:             data->endbyte_bits = 0;
yading@11:             buf++;
yading@11:             len--;
yading@11:             avio_w8(data->buf, data->endbyte);
yading@11:         } else {
yading@11:             /* Start/end skip bits not matching - missed packets? */
yading@11:             GetBitContext gb;
yading@11:             init_get_bits(&gb, buf, len*8 - ebit);
yading@11:             skip_bits(&gb, sbit);
yading@11:             if (data->endbyte_bits) {
yading@11:                 data->endbyte |= get_bits(&gb, 8 - data->endbyte_bits);
yading@11:                 avio_w8(data->buf, data->endbyte);
yading@11:             }
yading@11:             while (get_bits_left(&gb) >= 8)
yading@11:                 avio_w8(data->buf, get_bits(&gb, 8));
yading@11:             data->endbyte_bits = get_bits_left(&gb);
yading@11:             if (data->endbyte_bits)
yading@11:                 data->endbyte = get_bits(&gb, data->endbyte_bits) <<
yading@11:                                 (8 - data->endbyte_bits);
yading@11:             ebit = 0;
yading@11:             len = 0;
yading@11:         }
yading@11:     }
yading@11:     if (ebit) {
yading@11:         if (len > 0)
yading@11:             avio_write(data->buf, buf, len - 1);
yading@11:         data->endbyte_bits = 8 - ebit;
yading@11:         data->endbyte = buf[len - 1] & (0xff << ebit);
yading@11:     } else {
yading@11:         avio_write(data->buf, buf, len);
yading@11:     }
yading@11: 
yading@11:     if (!(flags & RTP_FLAG_MARKER))
yading@11:         return AVERROR(EAGAIN);
yading@11: 
yading@11:     if (data->endbyte_bits)
yading@11:         avio_w8(data->buf, data->endbyte);
yading@11:     data->endbyte_bits = 0;
yading@11: 
yading@11:     ret = ff_rtp_finalize_packet(pkt, &data->buf, st->index);
yading@11:     if (ret < 0)
yading@11:         return ret;
yading@11:     if (!i)
yading@11:         pkt->flags   |= AV_PKT_FLAG_KEY;
yading@11: 
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: RTPDynamicProtocolHandler ff_h263_rfc2190_dynamic_handler = {
yading@11:     .codec_type        = AVMEDIA_TYPE_VIDEO,
yading@11:     .codec_id          = AV_CODEC_ID_H263,
yading@11:     .init              = h263_init,
yading@11:     .parse_packet      = h263_handle_packet,
yading@11:     .alloc             = h263_new_context,
yading@11:     .free              = h263_free_context,
yading@11:     .static_payload_id = 34,
yading@11: };