static gboolean
dissect_mpeg_audio_frame(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
guint32 h;
struct mpa mpa;
int data_size = 0;
asn1_ctx_t asn1_ctx;
int offset = 0;
static const char *version_names[] = { "1", "2", "2.5" };
if (!tvb_bytes_exist(tvb, 0, 4))
return FALSE; /* not enough data for an MPEG audio frame */
h = tvb_get_ntohl(tvb, 0);
MPA_UNMARSHAL(&mpa, h);
if (!MPA_SYNC_VALID(&mpa))
return FALSE;
if (!MPA_VERSION_VALID(&mpa))
return FALSE;
if (!MPA_LAYER_VALID(&mpa))
return FALSE;
col_add_fstr(pinfo->cinfo, COL_PROTOCOL,
"MPEG-%s", version_names[mpa_version(&mpa)]);
col_add_fstr(pinfo->cinfo, COL_INFO,
"Audio Layer %d", mpa_layer(&mpa) + 1);
if (MPA_BITRATE_VALID(&mpa) && MPA_FREQUENCY_VALID(&mpa)) {
data_size = (int)(MPA_DATA_BYTES(&mpa) - sizeof mpa);
if (check_col(pinfo->cinfo, COL_DEF_SRC)) {
SET_ADDRESS(&pinfo->src, AT_NONE, 0, NULL);
col_add_fstr(pinfo->cinfo, COL_DEF_SRC,
"%d kb/s", mpa_bitrate(&mpa) / 1000);
}
if (check_col(pinfo->cinfo, COL_DEF_DST)) {
SET_ADDRESS(&pinfo->dst, AT_NONE, 0, NULL);
col_add_fstr(pinfo->cinfo, COL_DEF_DST,
"%g kHz", mpa_frequency(&mpa) / (float)1000);
}
}
if (tree == NULL)
return TRUE;
asn1_ctx_init(&asn1_ctx, ASN1_ENC_PER, TRUE, pinfo);
offset = dissect_mpeg_audio_Audio(tvb, offset, &asn1_ctx,
tree, proto_mpeg_audio);
if (data_size > 0) {
unsigned int padding;
proto_tree_add_item(tree, hf_mpeg_audio_data, tvb,
offset / 8, data_size, ENC_NA);
offset += data_size * 8;
padding = mpa_padding(&mpa);
if (padding > 0) {
proto_tree_add_item(tree, hf_mpeg_audio_padbytes, tvb,
offset / 8, padding, ENC_NA);
}
}
return TRUE;
}
unsigned
mpa_samples(const struct mpa *mpa)
{
return mpa_samples_data[mpa_versions[mpa->version]][mpa_layer(mpa)];
}
