libavformat/rtpdec_latm.c
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00001 
00022 #include "rtpdec_formats.h"
00023 #include "internal.h"
00024 #include "libavutil/avstring.h"
00025 #include "libavcodec/get_bits.h"
00026 
00027 struct PayloadContext {
00028     AVIOContext *dyn_buf;
00029     uint8_t *buf;
00030     int pos, len;
00031     uint32_t timestamp;
00032 };
00033 
00034 static PayloadContext *latm_new_context(void)
00035 {
00036     return av_mallocz(sizeof(PayloadContext));
00037 }
00038 
00039 static void latm_free_context(PayloadContext *data)
00040 {
00041     if (!data)
00042         return;
00043     if (data->dyn_buf) {
00044         uint8_t *p;
00045         avio_close_dyn_buf(data->dyn_buf, &p);
00046         av_free(p);
00047     }
00048     av_free(data->buf);
00049     av_free(data);
00050 }
00051 
00052 static int latm_parse_packet(AVFormatContext *ctx, PayloadContext *data,
00053                              AVStream *st, AVPacket *pkt, uint32_t *timestamp,
00054                              const uint8_t *buf, int len, int flags)
00055 {
00056     int ret, cur_len;
00057 
00058     if (buf) {
00059         if (!data->dyn_buf || data->timestamp != *timestamp) {
00060             av_freep(&data->buf);
00061             if (data->dyn_buf)
00062                 avio_close_dyn_buf(data->dyn_buf, &data->buf);
00063             data->dyn_buf = NULL;
00064             av_freep(&data->buf);
00065 
00066             data->timestamp = *timestamp;
00067             if ((ret = avio_open_dyn_buf(&data->dyn_buf)) < 0)
00068                 return ret;
00069         }
00070         avio_write(data->dyn_buf, buf, len);
00071 
00072         if (!(flags & RTP_FLAG_MARKER))
00073             return AVERROR(EAGAIN);
00074         av_free(data->buf);
00075         data->len = avio_close_dyn_buf(data->dyn_buf, &data->buf);
00076         data->dyn_buf = NULL;
00077         data->pos = 0;
00078     }
00079 
00080     if (!data->buf) {
00081         av_log(ctx, AV_LOG_ERROR, "No data available yet\n");
00082         return AVERROR(EIO);
00083     }
00084 
00085     cur_len = 0;
00086     while (data->pos < data->len) {
00087         uint8_t val = data->buf[data->pos++];
00088         cur_len += val;
00089         if (val != 0xff)
00090             break;
00091     }
00092     if (data->pos + cur_len > data->len) {
00093         av_log(ctx, AV_LOG_ERROR, "Malformed LATM packet\n");
00094         return AVERROR(EIO);
00095     }
00096 
00097     if ((ret = av_new_packet(pkt, cur_len)) < 0)
00098         return ret;
00099     memcpy(pkt->data, data->buf + data->pos, cur_len);
00100     data->pos += cur_len;
00101     pkt->stream_index = st->index;
00102     return data->pos < data->len;
00103 }
00104 
00105 static int parse_fmtp_config(AVStream *st, char *value)
00106 {
00107     int len = ff_hex_to_data(NULL, value), i, ret = 0;
00108     GetBitContext gb;
00109     uint8_t *config;
00110     int audio_mux_version, same_time_framing, num_programs, num_layers;
00111 
00112     /* Pad this buffer, too, to avoid out of bounds reads with get_bits below */
00113     config = av_mallocz(len + FF_INPUT_BUFFER_PADDING_SIZE);
00114     if (!config)
00115         return AVERROR(ENOMEM);
00116     ff_hex_to_data(config, value);
00117     init_get_bits(&gb, config, len*8);
00118     audio_mux_version = get_bits(&gb, 1);
00119     same_time_framing = get_bits(&gb, 1);
00120     skip_bits(&gb, 6); /* num_sub_frames */
00121     num_programs      = get_bits(&gb, 4);
00122     num_layers        = get_bits(&gb, 3);
00123     if (audio_mux_version != 0 || same_time_framing != 1 || num_programs != 0 ||
00124         num_layers != 0) {
00125         av_log(NULL, AV_LOG_WARNING, "Unsupported LATM config (%d,%d,%d,%d)\n",
00126                                      audio_mux_version, same_time_framing,
00127                                      num_programs, num_layers);
00128         ret = AVERROR_PATCHWELCOME;
00129         goto end;
00130     }
00131     av_freep(&st->codec->extradata);
00132     st->codec->extradata_size = (get_bits_left(&gb) + 7)/8;
00133     st->codec->extradata = av_mallocz(st->codec->extradata_size +
00134                                       FF_INPUT_BUFFER_PADDING_SIZE);
00135     if (!st->codec->extradata) {
00136         ret = AVERROR(ENOMEM);
00137         goto end;
00138     }
00139     for (i = 0; i < st->codec->extradata_size; i++)
00140         st->codec->extradata[i] = get_bits(&gb, 8);
00141 
00142 end:
00143     av_free(config);
00144     return ret;
00145 }
00146 
00147 static int parse_fmtp(AVStream *stream, PayloadContext *data,
00148                       char *attr, char *value)
00149 {
00150     int res;
00151 
00152     if (!strcmp(attr, "config")) {
00153         res = parse_fmtp_config(stream, value);
00154         if (res < 0)
00155             return res;
00156     } else if (!strcmp(attr, "cpresent")) {
00157         int cpresent = atoi(value);
00158         if (cpresent != 0)
00159             av_log_missing_feature(NULL, "RTP MP4A-LATM with in-band "
00160                                          "configuration", 1);
00161     }
00162 
00163     return 0;
00164 }
00165 
00166 static int latm_parse_sdp_line(AVFormatContext *s, int st_index,
00167                                PayloadContext *data, const char *line)
00168 {
00169     const char *p;
00170 
00171     if (av_strstart(line, "fmtp:", &p))
00172         return ff_parse_fmtp(s->streams[st_index], data, p, parse_fmtp);
00173 
00174     return 0;
00175 }
00176 
00177 RTPDynamicProtocolHandler ff_mp4a_latm_dynamic_handler = {
00178     .enc_name           = "MP4A-LATM",
00179     .codec_type         = AVMEDIA_TYPE_AUDIO,
00180     .codec_id           = CODEC_ID_AAC,
00181     .parse_sdp_a_line   = latm_parse_sdp_line,
00182     .alloc              = latm_new_context,
00183     .free               = latm_free_context,
00184     .parse_packet       = latm_parse_packet
00185 };