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rtpdec_jpeg: Add support for default quantizers

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Generate quantization tables when they are not present in the
first chunk.

Signed-off-by: Martin Storsjö <martin@martin.st>
This commit is contained in:
Samuel Pitoiset 2012-09-10 21:15:09 +02:00 committed by Martin Storsjö
parent 1648a508fa
commit 55e778bebd
1 changed files with 47 additions and 3 deletions
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50
libavformat/rtpdec_jpeg.c
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@ -33,6 +33,28 @@ struct PayloadContext {
int hdr_size; ///< size of the current frame header
};
static const uint8_t default_quantizers[128] = {
/* luma table */
16, 11, 12, 14, 12, 10, 16, 14,
13, 14, 18, 17, 16, 19, 24, 40,
26, 24, 22, 22, 24, 49, 35, 37,
29, 40, 58, 51, 61, 60, 57, 51,
56, 55, 64, 72, 92, 78, 64, 68,
87, 69, 55, 56, 80, 109, 81, 87,
95, 98, 103, 104, 103, 62, 77, 113,
121, 112, 100, 120, 92, 101, 103, 99,
/* chroma table */
17, 18, 18, 24, 21, 24, 47, 26,
26, 47, 99, 66, 56, 66, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99
};
static PayloadContext *jpeg_new_context(void)
{
return av_mallocz(sizeof(PayloadContext));
@ -170,6 +192,27 @@ static int jpeg_create_header(uint8_t *buf, int size, uint32_t type, uint32_t w,
return put_bits_count(&pbc) / 8;
}
static void create_default_qtables(uint8_t *qtables, uint8_t q)
{
int factor = q;
int i;
factor = av_clip(q, 1, 99);
if (q < 50)
q = 5000 / factor;
else
q = 200 - factor * 2;
for (i = 0; i < 128; i++) {
int val = (default_quantizers[i] * q + 50) / 100;
/* Limit the quantizers to 1 <= q <= 255. */
val = av_clip(val, 1, 255);
qtables[i] = val;
}
}
static int jpeg_parse_packet(AVFormatContext *ctx, PayloadContext *jpeg,
AVStream *st, AVPacket *pkt, uint32_t *timestamp,
const uint8_t *buf, int len, int flags)
@ -238,6 +281,7 @@ static int jpeg_parse_packet(AVFormatContext *ctx, PayloadContext *jpeg,
if (off == 0) {
/* Start of JPEG data packet. */
uint8_t new_qtables[128];
uint8_t hdr[1024];
/* Skip the current frame in case of the end packet
@ -249,9 +293,9 @@ static int jpeg_parse_packet(AVFormatContext *ctx, PayloadContext *jpeg,
jpeg->timestamp = *timestamp;
if (!qtables) {
av_log(ctx, AV_LOG_ERROR,
"Unimplemented default quantization tables.\n");
return AVERROR_PATCHWELCOME;
create_default_qtables(new_qtables, q);
qtables = new_qtables;
qtable_len = sizeof(new_qtables);
}
/* Generate a frame and scan headers that can be prepended to the