--- /dev/null
+/*
+ * RTP parser for H.261 payload format (RFC 4587)
+ * Copyright (c) 2014 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 "avformat.h"
+#include "rtpdec_formats.h"
+#include "libavcodec/get_bits.h"
+
+#define RTP_H261_PAYLOAD_HEADER_SIZE 4
+
+struct PayloadContext {
+ AVIOContext *buf;
+ uint8_t endbyte;
+ int endbyte_bits;
+ uint32_t timestamp;
+};
+
+static PayloadContext *h261_new_context(void)
+{
+ return av_mallocz(sizeof(PayloadContext));
+}
+
+static void h261_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 void h261_free_context(PayloadContext *pl_ctx)
+{
+ /* return if context is invalid */
+ if (!pl_ctx)
+ return;
+
+ /* free buffer if it is valid */
+ if (pl_ctx->buf) {
+ h261_free_dyn_buffer(&pl_ctx->buf);
+ }
+
+ /* free context */
+ av_free(pl_ctx);
+}
+
+static av_cold int h261_init(AVFormatContext *ctx, int st_index,
+ PayloadContext *data)
+{
+ //av_log(ctx, AV_LOG_DEBUG, "h261_init() for stream %d\n", st_index);
+
+ if (st_index < 0)
+ return 0;
+
+ ctx->streams[st_index]->need_parsing = AVSTREAM_PARSE_FULL;
+
+ return 0;
+}
+
+int ff_h261_handle_packet(AVFormatContext *ctx, PayloadContext *data,
+ AVStream *st, AVPacket *pkt, uint32_t *timestamp,
+ const uint8_t *buf, int len, uint16_t seq, int flags)
+{
+ int sbit, ebit, gobn, mbap, quant;
+ int res;
+
+ //av_log(ctx, AV_LOG_DEBUG, "got h261 RTP packet with time: %u\n", timestamp);
+
+ /* drop data of previous packets in case of non-continuous (loss) packet stream */
+ if (data->buf && data->timestamp != *timestamp) {
+ h261_free_dyn_buffer(&data->buf);
+ }
+
+ /* sanity check for size of input packet */
+ if (len < 5 /* 4 bytes header and 1 byte payload at least */) {
+ av_log(ctx, AV_LOG_ERROR, "Too short H.261 RTP packet\n");
+ return AVERROR_INVALIDDATA;
+ }
+
+ /*
+ decode the H.261 payload header according to section 4.1 of RFC 4587:
+ (uses 4 bytes between RTP header and H.261 stream per packet)
+
+ 0 1 2 3
+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ |SBIT |EBIT |I|V| GOBN | MBAP | QUANT | HMVD | VMVD |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+ Start bit position (SBIT): 3 bits
+ End bit position (EBIT): 3 bits
+ INTRA-frame encoded data (I): 1 bit
+ Motion Vector flag (V): 1 bit
+ GOB number (GOBN): 4 bits
+ Macroblock address predictor (MBAP): 5 bits
+ Quantizer (QUANT): 5 bits
+ Horizontal motion vector data (HMVD): 5 bits
+ Vertical motion vector data (VMVD): 5 bits
+
+ */
+ sbit = (buf[0] >> 5) & 0x07;
+ ebit = (buf[0] >> 2) & 0x07;
+ gobn = (buf[1] >> 4) & 0x0f;
+ mbap = ((buf[1] << 1) & 0x1e) | ((buf[1] >> 7) & 0x01);
+ quant = (buf[1] >> 4) & 0x0f;
+
+ /* pass the H.261 payload header and continue with the actual payload */
+ buf += RTP_H261_PAYLOAD_HEADER_SIZE;
+ len -= RTP_H261_PAYLOAD_HEADER_SIZE;
+
+ /* start frame buffering with new dynamic buffer */
+ if (!data->buf) {
+ /* sanity check: a new frame starts with gobn=0, sbit=0, mbap=0, uqnat=0 */
+ if (!gobn && !sbit && !mbap && !quant){
+ res = avio_open_dyn_buf(&data->buf);
+ if (res < 0)
+ return res;
+ /* update the timestamp in the frame packet with the one from the RTP packet */
+ data->timestamp = *timestamp;
+ } else {
+ /* frame not started yet, need more packets */
+ return AVERROR(EAGAIN);
+ }
+ }
+
+ /* do the "byte merging" at the boundaries of two consecutive frame fragments */
+ if (data->endbyte_bits || sbit) {
+ if (data->endbyte_bits == sbit) {
+ data->endbyte |= buf[0] & (0xff >> sbit);
+ data->endbyte_bits = 0;
+ buf++;
+ len--;
+ avio_w8(data->buf, data->endbyte);
+ } else {
+ /* ebit/sbit values inconsistent, assuming packet loss */
+ GetBitContext gb;
+ init_get_bits(&gb, buf, len*8 - ebit);
+ skip_bits(&gb, sbit);
+ if (data->endbyte_bits) {
+ data->endbyte |= get_bits(&gb, 8 - data->endbyte_bits);
+ avio_w8(data->buf, data->endbyte);
+ }
+ while (get_bits_left(&gb) >= 8)
+ avio_w8(data->buf, get_bits(&gb, 8));
+ data->endbyte_bits = get_bits_left(&gb);
+ if (data->endbyte_bits)
+ data->endbyte = get_bits(&gb, data->endbyte_bits) <<
+ (8 - data->endbyte_bits);
+ ebit = 0;
+ len = 0;
+ }
+ }
+ if (ebit) {
+ if (len > 0)
+ avio_write(data->buf, buf, len - 1);
+ data->endbyte_bits = 8 - ebit;
+ data->endbyte = buf[len - 1] & (0xff << ebit);
+ } else {
+ avio_write(data->buf, buf, len);
+ }
+
+ /* RTP marker bit means: last fragment of current frame was received;
+ otherwise, an additional fragment is needed for the current frame */
+ if (!(flags & RTP_FLAG_MARKER))
+ return AVERROR(EAGAIN);
+
+ /* write the completed last byte from the "byte merging" */
+ if (data->endbyte_bits)
+ avio_w8(data->buf, data->endbyte);
+ data->endbyte_bits = 0;
+
+ /* close frame buffering and create resulting A/V packet */
+ res = ff_rtp_finalize_packet(pkt, &data->buf, st->index);
+ if (res < 0)
+ return res;
+
+ return 0;
+}
+
+RTPDynamicProtocolHandler ff_h261_dynamic_handler = {
+ .enc_name = "H261",
+ .codec_type = AVMEDIA_TYPE_VIDEO,
+ .codec_id = AV_CODEC_ID_H261,
+ .init = h261_init,
+ .parse_packet = ff_h261_handle_packet,
+ .alloc = h261_new_context,
+ .free = h261_free_context,
+ .static_payload_id = 31,
+};
--- /dev/null
+/*
+ * RTP packetization for H.261 video (RFC 4587)
+ * Copyright (c) 2014 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 "avformat.h"
+#include "rtpenc.h"
+
+void ff_rtp_send_h261(AVFormatContext *s1, const uint8_t *frame_buf, int frame_size)
+{
+ RTPMuxContext *rtp_ctx = s1->priv_data;
+ int processed_frame_size;
+ int last_packet_of_frame;
+ uint8_t *tmp_buf_ptr;
+
+ /* use the default 90 KHz time stamp */
+ rtp_ctx->timestamp = rtp_ctx->cur_timestamp;
+
+ /* continue as long as not all frame data is processed */
+ while (frame_size > 0) {
+ tmp_buf_ptr = rtp_ctx->buf;
+ *tmp_buf_ptr++ = 1; /* V=1 */
+ *tmp_buf_ptr++ = 0;
+ *tmp_buf_ptr++ = 0;
+ *tmp_buf_ptr++ = 0;
+
+ processed_frame_size = FFMIN(rtp_ctx->max_payload_size - 4, frame_size);
+
+ //XXX: parse the h.261 bitstream and improve frame splitting here
+
+ last_packet_of_frame = (processed_frame_size == frame_size);
+
+ memcpy(tmp_buf_ptr, frame_buf, processed_frame_size);
+ tmp_buf_ptr += processed_frame_size;
+
+ ff_rtp_send_data(s1, rtp_ctx->buf, tmp_buf_ptr - rtp_ctx->buf, last_packet_of_frame);
+
+ frame_buf += processed_frame_size;
+ frame_size -= processed_frame_size;
+ }
+}