When the header is packed before sending to the driver through LibVA,
It is neccesary to normalize the quality factor and scale the Quantization
tables based on this quality factor.
---
test/encode/jpegenc.c | 38 ++++++++++++++++++++++++++++++++++----
1 file changed, 34 insertions(+), 4 deletions(-)
diff --git a/test/encode/jpegenc.c b/test/encode/jpegenc.c
index ff7a45a..9179b70 100644
--- a/test/encode/jpegenc.c
+++ b/test/encode/jpegenc.c
@@ -27,7 +27,10 @@
* Usage:
* ./jpegenc <width> <height> <input file> <output file> <input filetype
0(I420)/1(NV12)/2(UYVY)/3(YUY2)/4(Y8)/5(RGBA)> q <quality>
* Currently supporting only I420/NV12/UYVY/YUY2/Y8 input file formats.
- */
+ *
+ * NOTE: The intel-driver expects a packed header sent to it. So, the app is
responsible to pack the header
+ * and send to the driver through LibVA. This unit test also showcases how to
send the header to the driver.
+ */
#include "sysdeps.h"
#include <stdio.h>
@@ -310,11 +313,15 @@ void populate_scan_header(JPEGScanHeader *scanHdr,
YUVComponentSpecs yuvComp)
}
-
-int build_packed_jpeg_header_buffer(unsigned char **header_buffer,
YUVComponentSpecs yuvComp, int picture_width, int picture_height, uint16_t
restart_interval)
+// This method packs the header information which is to be sent to the driver
through LibVA.
+// All the information that needs to be inserted in the encoded buffer should
be built and sent.
+// It is the responsibility of the app talking to LibVA to build this header
and send it.
+// This includes Markers, Quantization tables (normalized with quality
factor), Huffman tables,etc.
+int build_packed_jpeg_header_buffer(unsigned char **header_buffer,
YUVComponentSpecs yuvComp, int picture_width, int picture_height, uint16_t
restart_interval, int quality)
{
bitstream bs;
int i=0, j=0;
+ uint32_t temp=0;
bitstream_start(&bs);
@@ -336,6 +343,17 @@ int build_packed_jpeg_header_buffer(unsigned char
**header_buffer, YUVComponentS
bitstream_put_ui(&bs, 72, 16); //Y density
bitstream_put_ui(&bs, 0, 8); //Thumbnail width
bitstream_put_ui(&bs, 0, 8); //Thumbnail height
+
+ // Regarding Quantization matrices: As per JPEG Spec ISO/IEC
10918-1:1993(E), Pg-19:
+ // "applications may specify values which customize picture quality for
their particular
+ // image characteristics, display devices, and viewing conditions"
+
+
+ //Normalization of quality factor
+ if(quality >= 100) quality=100;
+ if(quality <= 0) quality=1;
+
+ quality = (quality < 50) ? (5000/quality) : (200 - (quality*2));
//Add QTable - Y
JPEGQuantSection quantLuma;
@@ -346,6 +364,12 @@ int build_packed_jpeg_header_buffer(unsigned char
**header_buffer, YUVComponentS
bitstream_put_ui(&bs, quantLuma.Pq, 4);
bitstream_put_ui(&bs, quantLuma.Tq, 4);
for(i=0; i<NUM_QUANT_ELEMENTS; i++) {
+ //scale the quantization table with quality factor
+ temp = (quantLuma.Qk[i] * quality)/100;
+ //clamp to range [1,255]
+ temp = (temp > 255) ? 255 : temp;
+ temp = (temp < 1) ? 1 : temp;
+ quantLuma.Qk[i] = (unsigned char)temp;
bitstream_put_ui(&bs, quantLuma.Qk[i], 8);
}
@@ -359,6 +383,12 @@ int build_packed_jpeg_header_buffer(unsigned char
**header_buffer, YUVComponentS
bitstream_put_ui(&bs, quantChroma.Pq, 4);
bitstream_put_ui(&bs, quantChroma.Tq, 4);
for(i=0; i<NUM_QUANT_ELEMENTS; i++) {
+ //scale the quantization table with quality factor
+ temp = (quantChroma.Qk[i] * quality)/100;
+ //clamp to range [1,255]
+ temp = (temp > 255) ? 255 : temp;
+ temp = (temp < 1) ? 1 : temp;
+ quantChroma.Qk[i] = (unsigned char)temp;
bitstream_put_ui(&bs, quantChroma.Qk[i], 8);
}
}
@@ -778,7 +808,7 @@ int encode_input_image(FILE *yuv_fp, FILE *jpeg_fp, int
picture_width, int pictu
unsigned int length_in_bits;
unsigned char *packed_header_buffer = NULL;
- length_in_bits = build_packed_jpeg_header_buffer(&packed_header_buffer,
yuvComponent, picture_width, picture_height, slice_param.restart_interval);
+ length_in_bits = build_packed_jpeg_header_buffer(&packed_header_buffer,
yuvComponent, picture_width, picture_height, slice_param.restart_interval,
quality);
packed_header_param_buffer.type = VAEncPackedHeaderRawData;
packed_header_param_buffer.bit_length = length_in_bits;
packed_header_param_buffer.has_emulation_bytes = 0;
--
1.9.1
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