[deb_ffmpeg.git] / ffmpeg / libavformat / rtpdec_h261.c

/*
 * 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[2] >> 7) & 0x01);
    quant =  (buf[2] >> 2) & 0x1f;

    /* 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,
};
Commit	Line	Data
2ba45a60 DM	1	/*
	2	* RTP parser for H.261 payload format (RFC 4587)
	3	* Copyright (c) 2014 Thomas Volkert <thomas@homer-conferencing.com>
	4	*
	5	* This file is part of FFmpeg.
	6	*
	7	* FFmpeg is free software; you can redistribute it and/or
	8	* modify it under the terms of the GNU Lesser General Public
	9	* License as published by the Free Software Foundation; either
	10	* version 2.1 of the License, or (at your option) any later version.
	11	*
	12	* FFmpeg is distributed in the hope that it will be useful,
	13	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	15	* Lesser General Public License for more details.
	16	*
	17	* You should have received a copy of the GNU Lesser General Public
	18	* License along with FFmpeg; if not, write to the Free Software
	19	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	20	*/
	21
	22	#include "avformat.h"
	23	#include "rtpdec_formats.h"
	24	#include "libavcodec/get_bits.h"
	25
	26	#define RTP_H261_PAYLOAD_HEADER_SIZE 4
	27
	28	struct PayloadContext {
	29	AVIOContext *buf;
	30	uint8_t endbyte;
	31	int endbyte_bits;
	32	uint32_t timestamp;
	33	};
	34
	35	static PayloadContext *h261_new_context(void)
	36	{
	37	return av_mallocz(sizeof(PayloadContext));
	38	}
	39
	40	static void h261_free_dyn_buffer(AVIOContext **dyn_buf)
	41	{
	42	uint8_t *ptr_dyn_buffer;
	43	avio_close_dyn_buf(*dyn_buf, &ptr_dyn_buffer);
	44	av_free(ptr_dyn_buffer);
	45	*dyn_buf = NULL;
	46	}
	47
	48	static void h261_free_context(PayloadContext *pl_ctx)
	49	{
	50	/* return if context is invalid */
	51	if (!pl_ctx)
	52	return;
	53
	54	/* free buffer if it is valid */
	55	if (pl_ctx->buf) {
	56	h261_free_dyn_buffer(&pl_ctx->buf);
	57	}
	58
	59	/* free context */
	60	av_free(pl_ctx);
	61	}
	62
	63	static av_cold int h261_init(AVFormatContext *ctx, int st_index,
	64	PayloadContext *data)
65	{
66	//av_log(ctx, AV_LOG_DEBUG, "h261_init() for stream %d\n", st_index);
67
68	if (st_index < 0)
69	return 0;
70
71	ctx->streams[st_index]->need_parsing = AVSTREAM_PARSE_FULL;
72
73	return 0;
74	}
75
76	int ff_h261_handle_packet(AVFormatContext ctx, PayloadContext data,
77	AVStream st, AVPacket pkt, uint32_t *timestamp,
78	const uint8_t *buf, int len, uint16_t seq, int flags)
79	{
80	int sbit, ebit, gobn, mbap, quant;
81	int res;
82
83	//av_log(ctx, AV_LOG_DEBUG, "got h261 RTP packet with time: %u\n", timestamp);
84
85	/* drop data of previous packets in case of non-continuous (loss) packet stream */
86	if (data->buf && data->timestamp != *timestamp) {
87	h261_free_dyn_buffer(&data->buf);
88	}
89
90	/* sanity check for size of input packet */
91	if (len < 5 /* 4 bytes header and 1 byte payload at least */) {
92	av_log(ctx, AV_LOG_ERROR, "Too short H.261 RTP packet\n");
93	return AVERROR_INVALIDDATA;
94	}
95
96	/*
97	decode the H.261 payload header according to section 4.1 of RFC 4587:
98	(uses 4 bytes between RTP header and H.261 stream per packet)
99
100	0 1 2 3
101	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
102	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
103	\|SBIT \|EBIT \|I\|V\| GOBN \| MBAP \| QUANT \| HMVD \| VMVD \|
104	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
105
106	Start bit position (SBIT): 3 bits
107	End bit position (EBIT): 3 bits
108	INTRA-frame encoded data (I): 1 bit
109	Motion Vector flag (V): 1 bit
110	GOB number (GOBN): 4 bits
111	Macroblock address predictor (MBAP): 5 bits
112	Quantizer (QUANT): 5 bits
113	Horizontal motion vector data (HMVD): 5 bits
114	Vertical motion vector data (VMVD): 5 bits
115
116	*/
117	sbit = (buf[0] >> 5) & 0x07;
118	ebit = (buf[0] >> 2) & 0x07;
119	gobn = (buf[1] >> 4) & 0x0f;
120	mbap = ((buf[1] << 1) & 0x1e) \| ((buf[2] >> 7) & 0x01);
121	quant = (buf[2] >> 2) & 0x1f;
122
123	/* pass the H.261 payload header and continue with the actual payload */
124	buf += RTP_H261_PAYLOAD_HEADER_SIZE;
125	len -= RTP_H261_PAYLOAD_HEADER_SIZE;
126
127	/* start frame buffering with new dynamic buffer */
128	if (!data->buf) {
129	/* sanity check: a new frame starts with gobn=0, sbit=0, mbap=0, uqnat=0 */
130	if (!gobn && !sbit && !mbap && !quant){
131	res = avio_open_dyn_buf(&data->buf);
132	if (res < 0)
133	return res;
134	/* update the timestamp in the frame packet with the one from the RTP packet */
135	data->timestamp = *timestamp;
136	} else {
137	/* frame not started yet, need more packets */
138	return AVERROR(EAGAIN);
139	}
140	}
141
142	/* do the "byte merging" at the boundaries of two consecutive frame fragments */
143	if (data->endbyte_bits \|\| sbit) {
144	if (data->endbyte_bits == sbit) {
145	data->endbyte \|= buf[0] & (0xff >> sbit);
146	data->endbyte_bits = 0;
147	buf++;
148	len--;
149	avio_w8(data->buf, data->endbyte);
150	} else {
151	/* ebit/sbit values inconsistent, assuming packet loss */
152	GetBitContext gb;
153	init_get_bits(&gb, buf, len*8 - ebit);
154	skip_bits(&gb, sbit);
155	if (data->endbyte_bits) {
156	data->endbyte \|= get_bits(&gb, 8 - data->endbyte_bits);
157	avio_w8(data->buf, data->endbyte);
158	}
159	while (get_bits_left(&gb) >= 8)
160	avio_w8(data->buf, get_bits(&gb, 8));
161	data->endbyte_bits = get_bits_left(&gb);
162	if (data->endbyte_bits)
163	data->endbyte = get_bits(&gb, data->endbyte_bits) <<
164	(8 - data->endbyte_bits);
165	ebit = 0;
166	len = 0;
167	}
168	}
169	if (ebit) {
170	if (len > 0)
171	avio_write(data->buf, buf, len - 1);
172	data->endbyte_bits = 8 - ebit;
173	data->endbyte = buf[len - 1] & (0xff << ebit);
174	} else {
175	avio_write(data->buf, buf, len);
176	}
177
178	/* RTP marker bit means: last fragment of current frame was received;
179	otherwise, an additional fragment is needed for the current frame */
180	if (!(flags & RTP_FLAG_MARKER))
181	return AVERROR(EAGAIN);
182
183	/* write the completed last byte from the "byte merging" */
184	if (data->endbyte_bits)
185	avio_w8(data->buf, data->endbyte);
186	data->endbyte_bits = 0;
187
188	/* close frame buffering and create resulting A/V packet */
189	res = ff_rtp_finalize_packet(pkt, &data->buf, st->index);
190	if (res < 0)
191	return res;
192
193	return 0;
194	}
195
196	RTPDynamicProtocolHandler ff_h261_dynamic_handler = {
197	.enc_name = "H261",
198	.codec_type = AVMEDIA_TYPE_VIDEO,
199	.codec_id = AV_CODEC_ID_H261,
200	.init = h261_init,
201	.parse_packet = ff_h261_handle_packet,
202	.alloc = h261_new_context,
203	.free = h261_free_context,
204	.static_payload_id = 31,
205	};