decoder: add alignment option

refers to <#107>

Author: MartinPulec

CMakeLists.txt

@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.10.0 FATAL_ERROR)
 # change version also in configure.ac
-project(gpujpeg VERSION 0.27.12 LANGUAGES C CUDA)
+project(gpujpeg VERSION 0.27.13 LANGUAGES C CUDA)
 
 # options
 set(BUILD_OPENGL OFF CACHE STRING "Build with OpenGL support, options are: AUTO ON OFF")

NEWS.md

@@ -1,3 +1,8 @@
+2026-03-19 - 0.27.13
+----------
+
+- add decoder option GPUJPEG_DEC_OPT_ALIGNMENT_BYTES_INT (GH-107)
+
 2026-02-18 - 0.27.12
 ----------
 

configure.ac

@@ -1,6 +1,6 @@
 AC_PREREQ([2.65])
 # change version also in CMakeLists.txt
-AC_INIT([libgpujpeg],[0.27.12],[https://github.com/CESNET/GPUJPEG/issues],[libgpujpeg],[https://github.com/CESNET/GPUJPEG])
+AC_INIT([libgpujpeg],[0.27.13],[https://github.com/CESNET/GPUJPEG/issues],[libgpujpeg],[https://github.com/CESNET/GPUJPEG])
 AC_CONFIG_MACRO_DIR([m4])
 AC_CONFIG_SRCDIR([src/main.c])
 AC_CONFIG_AUX_DIR([.])

libgpujpeg/gpujpeg_decoder.h

@@ -300,6 +300,9 @@ gpujpeg_decoder_get_image_info(uint8_t *image, size_t image_size, struct gpujpeg
 /// @copydoc GPUJPEG_ENC_OPT_CHANNEL_REMAP
 #define GPUJPEG_DEC_OPT_CHANNEL_REMAP "dec_opt_channel_remap"
 
+/// required line padding in bytes
+#define GPUJPEG_DEC_OPT_ALIGNMENT_BYTES_INT "dec_opt_alignment_bytes"
+
 /**
  * sets decoder option
  * @retval GPUJPEG_NOERR  option was sucessfully set

src/gpujpeg_decoder.c

@@ -1,6 +1,6 @@
 /**
  * @file
- * Copyright (c) 2011-2025, CESNET
+ * Copyright (c) 2011-2026, CESNET
  * Copyright (c) 2011, Silicon Genome, LLC.
  *
  * All rights reserved.
@@ -502,6 +502,10 @@ gpujpeg_decoder_set_option(struct gpujpeg_decoder* decoder, const char *opt, con
     if ( strcmp(opt, GPUJPEG_DEC_OPT_CHANNEL_REMAP) == 0 ) {
         return gpujpeg_opt_set_channel_remap(&decoder->coder, val, GPUJPEG_DEC_OPT_CHANNEL_REMAP);
     }
+    if ( strcmp(opt, GPUJPEG_DEC_OPT_ALIGNMENT_BYTES_INT) == 0 ) {
+        decoder->req_alignment = atoi(val);
+        return GPUJPEG_NOERR;
+    }
     ERROR_MSG("Invalid decoder option: %s!\n", opt);
     return GPUJPEG_ERROR;
 }
@@ -513,8 +517,10 @@ gpujpeg_decoder_print_options()
            "] - set decoder option (not) to output RLE TGA\n");
     printf("\t" GPUJPEG_DEC_OPT_FLIPPED_BOOL "=[" GPUJPEG_VAL_FALSE "|" GPUJPEG_VAL_TRUE
            "] - vertically flip the output image\n");
-    printf("\t" GPUJPEG_DEC_OPT_CHANNEL_REMAP "=XYZ[W] - input channel mapping, eg. '210F' for GBRX,\n"
+    printf("\t" GPUJPEG_DEC_OPT_CHANNEL_REMAP "=XYZ[W] - ouput channel mapping, eg. '210F' for GBRX,\n"
         "\t\t'210' for GBR; special placeholders 'F' and 'Z' to set a channel to all-ones or all-zeros\n");
+    printf("\t" GPUJPEG_DEC_OPT_ALIGNMENT_BYTES_INT "=<num> - output alignment in bytes,\n"
+        "\t\tshould not be used for gpujpegtool (cannot process)\n");
 }
 
 /* Documented at declaration */

src/gpujpeg_decoder_internal.h

@@ -1,6 +1,6 @@
 /**
  * @file
- * Copyright (c) 2011-2025, CESNET
+ * Copyright (c) 2011-2026, CESNET
  * Copyright (c) 2011, Silicon Genome, LLC.
  *
  * All rights reserved.
@@ -69,6 +69,7 @@ struct gpujpeg_decoder
     enum gpujpeg_color_space req_color_space;
     bool ff_cs_itu601_is_709; ///< if FFmpeg specific COM marker "CS=ITU601" present, interpret the data as
                               ///< limited-range BT.709 not BT.601
+    int req_alignment;        ///< required output alignment in bytes
 
     /// metadata associated with last decoded image
     struct gpujpeg_image_metadata metadata;

src/gpujpeg_reader.c

@@ -1581,9 +1581,15 @@ adjust_pixel_format(struct gpujpeg_parameters * param, struct gpujpeg_image_para
     return param_image->pixel_format == GPUJPEG_PIXFMT_NO_ALPHA ? GPUJPEG_444_U8_P012 : GPUJPEG_4444_U8_P0123;
 }
 
+/**
+ * Adjust the unbound/unset parameters to match JPEG image properties.
+ *
+ * The main reason is to adnust the @ref gpujpeg_parameters and @ref gpujpeg_image_parameters
+ * to be consistend and/or match user requirements.
+ */
 static void
-adjust_format(struct gpujpeg_parameters* param, struct gpujpeg_image_parameters* param_image,
-              enum gpujpeg_color_space color_space_internal)
+adjust_params(struct gpujpeg_parameters* param, struct gpujpeg_image_parameters* param_image,
+              enum gpujpeg_color_space color_space_internal, unsigned req_alignment_b)
 {
     static_assert(GPUJPEG_PIXFMT_AUTODETECT < 0, "enum gpujpeg_pixel_format type should be signed");
     if ( param_image->color_space == GPUJPEG_NONE) {
@@ -1602,6 +1608,11 @@ adjust_format(struct gpujpeg_parameters* param, struct gpujpeg_image_parameters*
     if ( param_image->pixel_format <= GPUJPEG_PIXFMT_AUTODETECT ) {
         param_image->pixel_format = adjust_pixel_format(param, param_image);
     }
+    if (req_alignment_b != 0) {
+        const unsigned linesize_b = gpujpeg_pixel_format_get_unit_size(param_image->pixel_format) * param_image->width;
+        const unsigned aligned_linesize_b = (linesize_b + req_alignment_b - 1) / req_alignment_b * req_alignment_b;
+        param_image->width_padding = (int) (aligned_linesize_b - linesize_b);
+    }
 }
 
 /* Documented at declaration */
@@ -1669,7 +1680,8 @@ gpujpeg_reader_read_image(struct gpujpeg_decoder* decoder, uint8_t* image, size_
                                           reader.image_end) != 0 ) {
                 return -1;
             }
-            adjust_format(&reader.param, &reader.param_image, reader.param.color_space_internal);
+            adjust_params(&reader.param, &reader.param_image, reader.param.color_space_internal,
+                          decoder->req_alignment);
             break;
 
         case GPUJPEG_MARKER_DHT:
@@ -1774,7 +1786,7 @@ gpujpeg_reader_get_image_info(uint8_t *image, size_t image_size, struct gpujpeg_
                                           reader.image_end) != 0 ) {
                 return -1;
             }
-            adjust_format(&reader.param, &reader.param_image, reader.param.color_space_internal);
+            adjust_params(&reader.param, &reader.param_image, reader.param.color_space_internal, 0);
             break;
         }
         case GPUJPEG_MARKER_RST0: