1/**
2 * RTP Depacketization of QCELP/PureVoice, RFC 2658
3 * Copyright (c) 2010 Martin Storsjo
4 *
5 * This file is part of Libav.
6 *
7 * Libav 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 * Libav 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 Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22#include "rtpdec_formats.h"
23
24static const uint8_t frame_sizes[] = {
25    1, 4, 8, 17, 35
26};
27
28typedef struct {
29    int pos;
30    int size;
31    /* The largest frame is 35 bytes, only 10 frames are allowed per
32     * packet, and we return the first one immediately, so allocate
33     * space for 9 frames */
34    uint8_t data[35*9];
35} InterleavePacket;
36
37struct PayloadContext {
38    int interleave_size;
39    int interleave_index;
40    InterleavePacket group[6];
41    int group_finished;
42
43    /* The maximum packet size, 10 frames of 35 bytes each, and one
44     * packet header byte. */
45    uint8_t  next_data[1 + 35*10];
46    int      next_size;
47    uint32_t next_timestamp;
48};
49
50static PayloadContext *qcelp_new_context(void)
51{
52    return av_mallocz(sizeof(PayloadContext));
53}
54
55static void qcelp_free_context(PayloadContext *data)
56{
57    av_free(data);
58}
59
60static int return_stored_frame(AVFormatContext *ctx, PayloadContext *data,
61                               AVStream *st, AVPacket *pkt, uint32_t *timestamp,
62                               const uint8_t *buf, int len);
63
64static int store_packet(AVFormatContext *ctx, PayloadContext *data,
65                        AVStream *st, AVPacket *pkt, uint32_t *timestamp,
66                        const uint8_t *buf, int len)
67{
68    int interleave_size, interleave_index;
69    int frame_size, ret;
70    InterleavePacket* ip;
71
72    if (len < 2)
73        return AVERROR_INVALIDDATA;
74
75    interleave_size  = buf[0] >> 3 & 7;
76    interleave_index = buf[0]      & 7;
77
78    if (interleave_size > 5) {
79        av_log(ctx, AV_LOG_ERROR, "Invalid interleave size %d\n",
80                                   interleave_size);
81        return AVERROR_INVALIDDATA;
82    }
83    if (interleave_index > interleave_size) {
84        av_log(ctx, AV_LOG_ERROR, "Invalid interleave index %d/%d\n",
85                                   interleave_index, interleave_size);
86        return AVERROR_INVALIDDATA;
87    }
88    if (interleave_size != data->interleave_size) {
89        int i;
90        /* First packet, or changed interleave size */
91        data->interleave_size = interleave_size;
92        data->interleave_index = 0;
93        for (i = 0; i < 6; i++)
94            data->group[i].size = 0;
95    }
96
97    if (interleave_index < data->interleave_index) {
98        /* Wrapped around - missed the last packet of the previous group. */
99        if (data->group_finished) {
100            /* No more data in the packets in this interleaving group, just
101             * start processing the next one */
102            data->interleave_index = 0;
103        } else {
104            /* Stash away the current packet, emit everything we have of the
105             * previous group. */
106            for (; data->interleave_index <= interleave_size;
107                 data->interleave_index++)
108                data->group[data->interleave_index].size = 0;
109
110            if (len > sizeof(data->next_data))
111                return AVERROR_INVALIDDATA;
112            memcpy(data->next_data, buf, len);
113            data->next_size = len;
114            data->next_timestamp = *timestamp;
115            *timestamp = RTP_NOTS_VALUE;
116
117            data->interleave_index = 0;
118            return return_stored_frame(ctx, data, st, pkt, timestamp, buf, len);
119        }
120    }
121    if (interleave_index > data->interleave_index) {
122        /* We missed a packet */
123        for (; data->interleave_index < interleave_index;
124             data->interleave_index++)
125            data->group[data->interleave_index].size = 0;
126    }
127    data->interleave_index = interleave_index;
128
129    if (buf[1] >= FF_ARRAY_ELEMS(frame_sizes))
130        return AVERROR_INVALIDDATA;
131    frame_size = frame_sizes[buf[1]];
132    if (1 + frame_size > len)
133        return AVERROR_INVALIDDATA;
134
135    if (len - 1 - frame_size > sizeof(data->group[0].data))
136        return AVERROR_INVALIDDATA;
137
138    if ((ret = av_new_packet(pkt, frame_size)) < 0)
139        return ret;
140    memcpy(pkt->data, &buf[1], frame_size);
141    pkt->stream_index = st->index;
142
143    ip = &data->group[data->interleave_index];
144    ip->size = len - 1 - frame_size;
145    ip->pos = 0;
146    memcpy(ip->data, &buf[1 + frame_size], ip->size);
147    /* Each packet must contain the same number of frames according to the
148     * RFC. If there's no data left in this packet, there shouldn't be any
149     * in any of the other frames in the interleaving group either. */
150    data->group_finished = ip->size == 0;
151
152    if (interleave_index == interleave_size) {
153        data->interleave_index = 0;
154        return !data->group_finished;
155    } else {
156        data->interleave_index++;
157        return 0;
158    }
159}
160
161static int return_stored_frame(AVFormatContext *ctx, PayloadContext *data,
162                               AVStream *st, AVPacket *pkt, uint32_t *timestamp,
163                               const uint8_t *buf, int len)
164{
165    InterleavePacket* ip = &data->group[data->interleave_index];
166    int frame_size, ret;
167
168    if (data->group_finished && data->interleave_index == 0) {
169        *timestamp = data->next_timestamp;
170        ret = store_packet(ctx, data, st, pkt, timestamp, data->next_data,
171                           data->next_size);
172        data->next_size = 0;
173        return ret;
174    }
175
176    if (ip->size == 0) {
177        /* No stored data for this interleave block, output an empty packet */
178        if ((ret = av_new_packet(pkt, 1)) < 0)
179            return ret;
180        pkt->data[0] = 0; // Blank - could also be 14, Erasure
181    } else {
182        if (ip->pos >= ip->size)
183            return AVERROR_INVALIDDATA;
184        if (ip->data[ip->pos] >= FF_ARRAY_ELEMS(frame_sizes))
185            return AVERROR_INVALIDDATA;
186        frame_size = frame_sizes[ip->data[ip->pos]];
187        if (ip->pos + frame_size > ip->size)
188            return AVERROR_INVALIDDATA;
189
190        if ((ret = av_new_packet(pkt, frame_size)) < 0)
191            return ret;
192        memcpy(pkt->data, &ip->data[ip->pos], frame_size);
193
194        ip->pos += frame_size;
195        data->group_finished = ip->pos >= ip->size;
196    }
197    pkt->stream_index = st->index;
198
199    if (data->interleave_index == data->interleave_size) {
200        data->interleave_index = 0;
201        if (!data->group_finished)
202            return 1;
203        else
204            return data->next_size > 0;
205    } else {
206        data->interleave_index++;
207        return 1;
208    }
209}
210
211static int qcelp_parse_packet(AVFormatContext *ctx, PayloadContext *data,
212                              AVStream *st, AVPacket *pkt, uint32_t *timestamp,
213                              const uint8_t *buf, int len, int flags)
214{
215    if (buf)
216        return store_packet(ctx, data, st, pkt, timestamp, buf, len);
217    else
218        return return_stored_frame(ctx, data, st, pkt, timestamp, buf, len);
219}
220
221RTPDynamicProtocolHandler ff_qcelp_dynamic_handler = {
222    .enc_name           = "x-Purevoice",
223    .codec_type         = AVMEDIA_TYPE_AUDIO,
224    .codec_id           = CODEC_ID_QCELP,
225    .static_payload_id  = 12,
226    .alloc              = qcelp_new_context,
227    .free               = qcelp_free_context,
228    .parse_packet       = qcelp_parse_packet
229};
230