Added normalization and scaling of the quality factor and Quantization tables

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.

1 files changed, 34 insertions, 4 deletions

diff --git a/test/encode/jpegenc.c b/test/encode/jpegenc.c
index ff7a45a..56fa2f1 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 +343,14 @@ 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
+    quality = (quality < 50) ? (5000/quality) : (200 - (quality*2));
     
     //Add QTable - Y
     JPEGQuantSection quantLuma;
@@ -346,6 +361,12 @@ 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 +380,12 @@ 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);
         }
     }
@@ -667,6 +694,9 @@ int encode_input_image(FILE *yuv_fp, FILE *jpeg_fp, int picture_width, int pictu
     YUVComponentSpecs yuvComponent;
     int writeToFile = 1;
     
+    //Clamp the quality factor value to [1,100]
+    if(quality >= 100) quality=100;
+    if(quality <= 0) quality=1;
     
     fourcc.type =VASurfaceAttribPixelFormat;
     fourcc.flags=VA_SURFACE_ATTRIB_SETTABLE;
@@ -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;