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Do not add the preamble if the DTS stream is already padded, like DTS in 

wav. In that case, DTS can be transmitted through S/PDIF without
the IEC 61937 headers.

Patch by Anssi Hannula, anssi d hannula a iki d fi

Originally committed as revision 26160 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Anssi Hannula 2010-12-29 23:42:27 +00:00 committed by Carl Eugen Hoyos
parent 720ea2d5b2
commit cc6c0c7b52
1 changed files with 12 additions and 1 deletions
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13
libavformat/spdifenc.c
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@ -60,6 +60,7 @@ typedef struct IEC61937Context {
uint8_t *out_buf; ///< pointer to the outgoing data before byte-swapping
int out_bytes; ///< amount of outgoing bytes
int use_preamble; ///< preamble enabled (disabled for exactly pre-padded DTS)
int extra_bswap; ///< extra bswap for payload (for LE DTS => standard BE DTS)
uint8_t *hd_buf; ///< allocated buffer to concatenate hd audio frames
@ -153,6 +154,13 @@ static int spdif_header_dts(AVFormatContext *s, AVPacket *pkt)
}
ctx->pkt_offset = blocks << 7;
if (ctx->out_bytes == ctx->pkt_offset) {
/* The DTS stream fits exactly into the output stream, so skip the
* preamble as it would not fit in there. This is the case for dts
* discs and dts-in-wav. */
ctx->use_preamble = 0;
}
return 0;
}
@ -330,6 +338,7 @@ static int spdif_write_packet(struct AVFormatContext *s, AVPacket *pkt)
ctx->out_buf = pkt->data;
ctx->out_bytes = pkt->size;
ctx->length_code = FFALIGN(pkt->size, 2) << 3;
ctx->use_preamble = 1;
ctx->extra_bswap = 0;
ret = ctx->header_info(s, pkt);
@ -338,16 +347,18 @@ static int spdif_write_packet(struct AVFormatContext *s, AVPacket *pkt)
if (!ctx->pkt_offset)
return 0;
padding = (ctx->pkt_offset - BURST_HEADER_SIZE - ctx->out_bytes) >> 1;
padding = (ctx->pkt_offset - ctx->use_preamble * BURST_HEADER_SIZE - ctx->out_bytes) >> 1;
if (padding < 0) {
av_log(s, AV_LOG_ERROR, "bitrate is too high\n");
return AVERROR(EINVAL);
}
if (ctx->use_preamble) {
put_le16(s->pb, SYNCWORD1); //Pa
put_le16(s->pb, SYNCWORD2); //Pb
put_le16(s->pb, ctx->data_type); //Pc
put_le16(s->pb, ctx->length_code);//Pd
}
if (HAVE_BIGENDIAN ^ ctx->extra_bswap) {
put_buffer(s->pb, ctx->out_buf, ctx->out_bytes & ~1);