Libav 0.7.1
libavformat/rtpdec_qcelp.c
Go to the documentation of this file.
00001 
00022 #include "rtpdec_formats.h"
00023 
00024 static const uint8_t frame_sizes[] = {
00025     1, 4, 8, 17, 35
00026 };
00027 
00028 typedef struct {
00029     int pos;
00030     int size;
00031     /* The largest frame is 35 bytes, only 10 frames are allowed per
00032      * packet, and we return the first one immediately, so allocate
00033      * space for 9 frames */
00034     uint8_t data[35*9];
00035 } InterleavePacket;
00036 
00037 struct PayloadContext {
00038     int interleave_size;
00039     int interleave_index;
00040     InterleavePacket group[6];
00041     int group_finished;
00042 
00043     /* The maximum packet size, 10 frames of 35 bytes each, and one
00044      * packet header byte. */
00045     uint8_t  next_data[1 + 35*10];
00046     int      next_size;
00047     uint32_t next_timestamp;
00048 };
00049 
00050 static PayloadContext *qcelp_new_context(void)
00051 {
00052     return av_mallocz(sizeof(PayloadContext));
00053 }
00054 
00055 static void qcelp_free_context(PayloadContext *data)
00056 {
00057     av_free(data);
00058 }
00059 
00060 static int return_stored_frame(AVFormatContext *ctx, PayloadContext *data,
00061                                AVStream *st, AVPacket *pkt, uint32_t *timestamp,
00062                                const uint8_t *buf, int len);
00063 
00064 static int store_packet(AVFormatContext *ctx, PayloadContext *data,
00065                         AVStream *st, AVPacket *pkt, uint32_t *timestamp,
00066                         const uint8_t *buf, int len)
00067 {
00068     int interleave_size, interleave_index;
00069     int frame_size, ret;
00070     InterleavePacket* ip;
00071 
00072     if (len < 2)
00073         return AVERROR_INVALIDDATA;
00074 
00075     interleave_size  = buf[0] >> 3 & 7;
00076     interleave_index = buf[0]      & 7;
00077 
00078     if (interleave_size > 5) {
00079         av_log(ctx, AV_LOG_ERROR, "Invalid interleave size %d\n",
00080                                    interleave_size);
00081         return AVERROR_INVALIDDATA;
00082     }
00083     if (interleave_index > interleave_size) {
00084         av_log(ctx, AV_LOG_ERROR, "Invalid interleave index %d/%d\n",
00085                                    interleave_index, interleave_size);
00086         return AVERROR_INVALIDDATA;
00087     }
00088     if (interleave_size != data->interleave_size) {
00089         int i;
00090         /* First packet, or changed interleave size */
00091         data->interleave_size = interleave_size;
00092         data->interleave_index = 0;
00093         for (i = 0; i < 6; i++)
00094             data->group[i].size = 0;
00095     }
00096 
00097     if (interleave_index < data->interleave_index) {
00098         /* Wrapped around - missed the last packet of the previous group. */
00099         if (data->group_finished) {
00100             /* No more data in the packets in this interleaving group, just
00101              * start processing the next one */
00102             data->interleave_index = 0;
00103         } else {
00104             /* Stash away the current packet, emit everything we have of the
00105              * previous group. */
00106             for (; data->interleave_index <= interleave_size;
00107                  data->interleave_index++)
00108                 data->group[data->interleave_index].size = 0;
00109 
00110             if (len > sizeof(data->next_data))
00111                 return AVERROR_INVALIDDATA;
00112             memcpy(data->next_data, buf, len);
00113             data->next_size = len;
00114             data->next_timestamp = *timestamp;
00115             *timestamp = RTP_NOTS_VALUE;
00116 
00117             data->interleave_index = 0;
00118             return return_stored_frame(ctx, data, st, pkt, timestamp, buf, len);
00119         }
00120     }
00121     if (interleave_index > data->interleave_index) {
00122         /* We missed a packet */
00123         for (; data->interleave_index < interleave_index;
00124              data->interleave_index++)
00125             data->group[data->interleave_index].size = 0;
00126     }
00127     data->interleave_index = interleave_index;
00128 
00129     if (buf[1] >= FF_ARRAY_ELEMS(frame_sizes))
00130         return AVERROR_INVALIDDATA;
00131     frame_size = frame_sizes[buf[1]];
00132     if (1 + frame_size > len)
00133         return AVERROR_INVALIDDATA;
00134 
00135     if (len - 1 - frame_size > sizeof(data->group[0].data))
00136         return AVERROR_INVALIDDATA;
00137 
00138     if ((ret = av_new_packet(pkt, frame_size)) < 0)
00139         return ret;
00140     memcpy(pkt->data, &buf[1], frame_size);
00141     pkt->stream_index = st->index;
00142 
00143     ip = &data->group[data->interleave_index];
00144     ip->size = len - 1 - frame_size;
00145     ip->pos = 0;
00146     memcpy(ip->data, &buf[1 + frame_size], ip->size);
00147     /* Each packet must contain the same number of frames according to the
00148      * RFC. If there's no data left in this packet, there shouldn't be any
00149      * in any of the other frames in the interleaving group either. */
00150     data->group_finished = ip->size == 0;
00151 
00152     if (interleave_index == interleave_size) {
00153         data->interleave_index = 0;
00154         return !data->group_finished;
00155     } else {
00156         data->interleave_index++;
00157         return 0;
00158     }
00159 }
00160 
00161 static int return_stored_frame(AVFormatContext *ctx, PayloadContext *data,
00162                                AVStream *st, AVPacket *pkt, uint32_t *timestamp,
00163                                const uint8_t *buf, int len)
00164 {
00165     InterleavePacket* ip = &data->group[data->interleave_index];
00166     int frame_size, ret;
00167 
00168     if (data->group_finished && data->interleave_index == 0) {
00169         *timestamp = data->next_timestamp;
00170         ret = store_packet(ctx, data, st, pkt, timestamp, data->next_data,
00171                            data->next_size);
00172         data->next_size = 0;
00173         return ret;
00174     }
00175 
00176     if (ip->size == 0) {
00177         /* No stored data for this interleave block, output an empty packet */
00178         if ((ret = av_new_packet(pkt, 1)) < 0)
00179             return ret;
00180         pkt->data[0] = 0; // Blank - could also be 14, Erasure
00181     } else {
00182         if (ip->pos >= ip->size)
00183             return AVERROR_INVALIDDATA;
00184         if (ip->data[ip->pos] >= FF_ARRAY_ELEMS(frame_sizes))
00185             return AVERROR_INVALIDDATA;
00186         frame_size = frame_sizes[ip->data[ip->pos]];
00187         if (ip->pos + frame_size > ip->size)
00188             return AVERROR_INVALIDDATA;
00189 
00190         if ((ret = av_new_packet(pkt, frame_size)) < 0)
00191             return ret;
00192         memcpy(pkt->data, &ip->data[ip->pos], frame_size);
00193 
00194         ip->pos += frame_size;
00195         data->group_finished = ip->pos >= ip->size;
00196     }
00197     pkt->stream_index = st->index;
00198 
00199     if (data->interleave_index == data->interleave_size) {
00200         data->interleave_index = 0;
00201         if (!data->group_finished)
00202             return 1;
00203         else
00204             return data->next_size > 0;
00205     } else {
00206         data->interleave_index++;
00207         return 1;
00208     }
00209 }
00210 
00211 static int qcelp_parse_packet(AVFormatContext *ctx, PayloadContext *data,
00212                               AVStream *st, AVPacket *pkt, uint32_t *timestamp,
00213                               const uint8_t *buf, int len, int flags)
00214 {
00215     if (buf)
00216         return store_packet(ctx, data, st, pkt, timestamp, buf, len);
00217     else
00218         return return_stored_frame(ctx, data, st, pkt, timestamp, buf, len);
00219 }
00220 
00221 RTPDynamicProtocolHandler ff_qcelp_dynamic_handler = {
00222     .enc_name           = "x-Purevoice",
00223     .codec_type         = AVMEDIA_TYPE_AUDIO,
00224     .codec_id           = CODEC_ID_QCELP,
00225     .static_payload_id  = 12,
00226     .alloc              = qcelp_new_context,
00227     .free               = qcelp_free_context,
00228     .parse_packet       = qcelp_parse_packet
00229 };