ffmpeg resize

ffmpeg/README.md

@@ -1,7 +1,8 @@
 # FFmpeg
 
 1.  Examples
-    1. []   
+    1. [encode](encode.c)
+    1. [resize](resize.c)
 1.  Theory
     1. [Introduction](introduction.md)
     1. [libav](libav.md)

ffmpeg/encode.c

@@ -41,7 +41,7 @@ static void ffmpeg_encoder_set_frame_yuv_from_rgb(uint8_t *rgb) {
     sws_context = sws_getCachedContext(sws_context,
             c->width, c->height, AV_PIX_FMT_RGB24,
             c->width, c->height, AV_PIX_FMT_YUV420P,
-            0, 0, 0, 0);
+            0, NULL, NULL, NULL);
     sws_scale(sws_context, (const uint8_t * const *)&rgb, in_linesize, 0,
             c->height, frame->data, frame->linesize);
 }
@@ -151,7 +151,7 @@ void ffmpeg_encoder_start(const char *filename, int codec_id, int fps, int width
     frame->format = c->pix_fmt;
     frame->width  = c->width;
     frame->height = c->height;
-    ret = av_image_alloc(frame->data, frame->linesize, c->width, c->height, c->pix_fmt, 32);
+    ret = av_image_alloc(frame->data, frame->linesize, frame->width, frame->height, frame->format, 32);
     if (ret < 0) {
         fprintf(stderr, "Could not allocate raw picture buffer\n");
         exit(1);

ffmpeg/resize.c

@@ -0,0 +1,210 @@
+/*
+http://stackoverflow.com/questions/12831761/how-to-resize-a-picture-using-ffmpegs-sws-scale
+
+Upstream: encode.c
+*/
+
+#include <libavcodec/avcodec.h>
+#include <libavutil/imgutils.h>
+#include <libavutil/opt.h>
+#include <libswscale/swscale.h>
+
+static AVCodecContext *c = NULL;
+static AVFrame *frame;
+static AVFrame *frame2;
+static AVPacket pkt;
+static FILE *file;
+static struct SwsContext *sws_context = NULL;
+
+static void ffmpeg_encoder_init_frame(AVFrame **framep, int width, int height) {
+    int ret;
+    AVFrame *frame;
+    frame = av_frame_alloc();
+    if (!frame) {
+        fprintf(stderr, "Could not allocate video frame\n");
+        exit(1);
+    }
+    frame->format = c->pix_fmt;
+    frame->width  = width;
+    frame->height = height;
+    ret = av_image_alloc(frame->data, frame->linesize, frame->width, frame->height, frame->format, 32);
+    if (ret < 0) {
+        fprintf(stderr, "Could not allocate raw picture buffer\n");
+        exit(1);
+    }
+    *framep = frame;
+}
+
+static void ffmpeg_encoder_scale(uint8_t *rgb) {
+    sws_context = sws_getCachedContext(sws_context,
+            frame->width, frame->height, AV_PIX_FMT_YUV420P,
+            frame2->width, frame2->height, AV_PIX_FMT_YUV420P,
+            SWS_BICUBIC, NULL, NULL, NULL);
+    sws_scale(sws_context, (const uint8_t * const *)frame->data, frame->linesize, 0,
+            frame->height, frame2->data, frame2->linesize);
+}
+
+static void ffmpeg_encoder_set_frame_yuv_from_rgb(uint8_t *rgb) {
+    const int in_linesize[1] = { 3 * frame->width };
+    sws_context = sws_getCachedContext(sws_context,
+            frame->width, frame->height, AV_PIX_FMT_RGB24,
+            frame->width, frame->height, AV_PIX_FMT_YUV420P,
+            0, NULL, NULL, NULL);
+    sws_scale(sws_context, (const uint8_t * const *)&rgb, in_linesize, 0,
+            frame->height, frame->data, frame->linesize);
+}
+
+void generate_rgb(int width, int height, int pts, uint8_t **rgbp) {
+    int x, y, cur;
+    uint8_t *rgb = *rgbp;
+    rgb = realloc(rgb, 3 * sizeof(uint8_t) * height * width);
+    for (y = 0; y < height; y++) {
+        for (x = 0; x < width; x++) {
+            cur = 3 * (y * width + x);
+            rgb[cur + 0] = 0;
+            rgb[cur + 1] = 0;
+            rgb[cur + 2] = 0;
+            if ((frame->pts / 25) % 2 == 0) {
+                if (y < height / 2) {
+                    if (x < width / 2) {
+                        /* Black. */
+                    } else {
+                        rgb[cur + 0] = 255;
+                    }
+                } else {
+                    if (x < width / 2) {
+                        rgb[cur + 1] = 255;
+                    } else {
+                        rgb[cur + 2] = 255;
+                    }
+                }
+            } else {
+                if (y < height / 2) {
+                    rgb[cur + 0] = 255;
+                    if (x < width / 2) {
+                        rgb[cur + 1] = 255;
+                    } else {
+                        rgb[cur + 2] = 255;
+                    }
+                } else {
+                    if (x < width / 2) {
+                        rgb[cur + 1] = 255;
+                        rgb[cur + 2] = 255;
+                    } else {
+                        rgb[cur + 0] = 255;
+                        rgb[cur + 1] = 255;
+                        rgb[cur + 2] = 255;
+                    }
+                }
+            }
+        }
+    }
+    *rgbp = rgb;
+}
+
+void ffmpeg_encoder_start(const char *filename, int codec_id, int fps, int width, int height, float factor) {
+    AVCodec *codec;
+    int ret;
+    int width2 = width * factor;
+    int height2 = height * factor;
+    avcodec_register_all();
+    codec = avcodec_find_encoder(codec_id);
+    if (!codec) {
+        fprintf(stderr, "Codec not found\n");
+        exit(1);
+    }
+    c = avcodec_alloc_context3(codec);
+    if (!c) {
+        fprintf(stderr, "Could not allocate video codec context\n");
+        exit(1);
+    }
+    c->bit_rate = 400000;
+    c->width = width2;
+    c->height = height2;
+    c->time_base.num = 1;
+    c->time_base.den = fps;
+    c->gop_size = 10;
+    c->max_b_frames = 1;
+    c->pix_fmt = AV_PIX_FMT_YUV420P;
+    if (codec_id == AV_CODEC_ID_H264)
+        av_opt_set(c->priv_data, "preset", "slow", 0);
+    if (avcodec_open2(c, codec, NULL) < 0) {
+        fprintf(stderr, "Could not open codec\n");
+        exit(1);
+    }
+    file = fopen(filename, "wb");
+    if (!file) {
+        fprintf(stderr, "Could not open %s\n", filename);
+        exit(1);
+    }
+    ffmpeg_encoder_init_frame(&frame, width, height);
+    ffmpeg_encoder_init_frame(&frame2, width2, height2);
+}
+
+void ffmpeg_encoder_finish(void) {
+    uint8_t endcode[] = { 0, 0, 1, 0xb7 };
+    int got_output, ret;
+    do {
+        fflush(stdout);
+        ret = avcodec_encode_video2(c, &pkt, NULL, &got_output);
+        if (ret < 0) {
+            fprintf(stderr, "Error encoding frame\n");
+            exit(1);
+        }
+        if (got_output) {
+            fwrite(pkt.data, 1, pkt.size, file);
+            av_packet_unref(&pkt);
+        }
+    } while (got_output);
+    fwrite(endcode, 1, sizeof(endcode), file);
+    fclose(file);
+    avcodec_close(c);
+    av_free(c);
+    av_freep(&frame->data[0]);
+    av_frame_free(&frame);
+    av_freep(&frame2->data[0]);
+    av_frame_free(&frame2);
+}
+
+void ffmpeg_encoder_encode_frame(uint8_t *rgb) {
+    int ret, got_output;
+    ffmpeg_encoder_set_frame_yuv_from_rgb(rgb);
+    ffmpeg_encoder_scale(rgb);
+    frame2->pts = frame->pts;
+    av_init_packet(&pkt);
+    pkt.data = NULL;
+    pkt.size = 0;
+    ret = avcodec_encode_video2(c, &pkt, frame2, &got_output);
+    if (ret < 0) {
+        fprintf(stderr, "Error encoding frame\n");
+        exit(1);
+    }
+    if (got_output) {
+        fwrite(pkt.data, 1, pkt.size, file);
+        av_packet_unref(&pkt);
+    }
+}
+
+static void encode_example(float factor) {
+    char filename[255];
+    int pts;
+    int width = 320;
+    int height = 240;
+    uint8_t *rgb = NULL;
+    snprintf(filename, 255, "tmp." __FILE__ ".%.2f.h264", factor);
+    ffmpeg_encoder_start(filename, AV_CODEC_ID_H264, 25, width, height, factor);
+    for (pts = 0; pts < 100; pts++) {
+        frame->pts = pts;
+        generate_rgb(width, height, pts, &rgb);
+        ffmpeg_encoder_encode_frame(rgb);
+    }
+    ffmpeg_encoder_finish();
+    free(rgb);
+}
+
+int main(void) {
+    encode_example(0.5);
+    encode_example(1.0);
+    encode_example(2.0);
+    return EXIT_SUCCESS;
+}

opencl/README.md

@@ -14,6 +14,7 @@
     1.  [Introduction](introduction.md)
     1.  [Implementations](implementations.md)
     1.  [Alternatives](alternatives.md)
+        1.  [CUDA](cuda.md)
     1.  [Architecture](architecture.md)
     1.  [C](c.md)
     1.  [Host API](host-api.md)

opencl/alternatives.md

@@ -1,17 +1,29 @@
 # Alternatives
 
-## CUDA
-
-NVIDIA's. More closed since controlled by NVIDIA. Also more popular for the same reason as they are the Top Dog now.
-
-<https://www.reddit.com/r/programming/comments/49uw97/cuda_reverse_engineered_to_run_on_nonnvidia/>
-
-<https://en.wikipedia.org/wiki/CUDA> NVIDIA's, only runs in NVIDIA hardware. TODO could AMD implement it legally without paying royalties to NVIDIA?
+As of 2016, CUDA is the top cat.
 
 ## OpenMP
 
 <http://stackoverflow.com/questions/7263193/opencl-performance-vs-openmp>
 
+Directive based: you write stuff like:
+
+http://stackoverflow.com/questions/19494786/openacc-vs-openmp-mpi-differences
+
+    /* Fork a team of threads giving them their own copies of variables */
+    #pragma omp parallel private(nthreads, tid)
+    {
+        /* Obtain thread number */
+        tid = omp_get_thread_num();
+
+instead of compiling a kernel.
+
+## OpenACC
+
+<https://en.wikipedia.org/wiki/OpenACC>
+
+NVIDIA's OpenMP, similar to OpenMP: <http://stackoverflow.com/questions/19494786/openacc-vs-openmp-mpi-differences>
+
 ## RenderScript
 
 Google's choice for Android: <http://stackoverflow.com/questions/14385843/why-did-google-choose-renderscript-instead-of-opencl>
@@ -42,5 +54,10 @@ Microsoft's
 
 ## Unified parallel C
 
-- <https://en.wikipedia.org/wiki/Unified_Parallel_C>
-- OpenGL compute shaders <http://stackoverflow.com/questions/15868498/what-is-the-difference-between-opencl-and-opengls-compute-shader>
+<https://en.wikipedia.org/wiki/Unified_Parallel_C>
+
+## Compute shaders
+
+OpenGL compute shaders <http://stackoverflow.com/questions/15868498/what-is-the-difference-between-opencl-and-opengls-compute-shader>
+
+Easier to integrate with graphics stuff.

opencl/applications.md

@@ -23,7 +23,7 @@ Not surprising, since rendering is just a bunch of matrix multiplications, with
 
 Sparse: <http://stackoverflow.com/questions/3438826/sparse-matrix-multiplication-on-gpu-or-cpu>
 
-Bolt: C++ STL GPU powered implementation by AMD: <http://developer.amd.com/tools-and-sdks/opencl-zone/bolt-c-template-library/>
+Bolt: C++ STL GPU powered implementation by AMD: <http://developer.amd.com/tools-and-sdks/opencl-zone/bolt-c-template-library/> Other suggestions: <http://stackoverflow.com/questions/16438099/high-level-gpu-programming-in-c>
 
 ## Non-applications
 

opencl/cuda.md

@@ -0,0 +1,35 @@
+# CUDA
+
+NVIDIA's. More closed since controlled by NVIDIA. Also more popular for the same reason as they are the Top Dog now.
+
+## Run on AMD
+
+<https://www.reddit.com/r/programming/comments/49uw97/cuda_reverse_engineered_to_run_on_nonnvidia/>
+
+<https://en.wikipedia.org/wiki/CUDA> NVIDIA's, currently only runs in NVIDIA hardware: <http://stackoverflow.com/questions/12828268/is-it-possible-to-run-cuda-on-amd-gpus>
+
+TODO could AMD implement it legally without paying royalties to NVIDIA? Seems yes: <https://www.reddit.com/r/MachineLearning/comments/4di4os/deep_learning_is_so_dependent_on_nvidia_are_there/d1rwuxb>
+
+Vulkan also adds the ability to run SPIR-V. So it is likely that SPIR-V will be well supported in NVIDIA and AMD cards, and we could then compile CUDA to SPIR-V. Result: AMD can run CUDA, and NVIDIA can run OpenCL.
+
+<https://www.reddit.com/r/vulkan/comments/3snrdv/vulkan_or_opencl/>
+
+If GPUCC generates SPIR-V, problem solved. TODO does it?
+
+## GPUCC
+
+LLVM-based CUDA compiler. TODO output format?
+
+http://wujingyue.github.io/docs/gpucc-talk.pdf https://www.youtube.com/watch?v=JHfb8z-iSYk
+
+http://gpuocelot.gatech.edu/ is a precursor it seems https://code.google.com/archive/p/gpuocelot/
+
+## nvcc
+
+<https://en.wikipedia.org/wiki/NVIDIA_CUDA_Compiler>
+
+## CUDA C/C++
+
+The kernel language, like OpenCL C.
+
+Vs ISO: http://stackoverflow.com/questions/9846523/explanation-of-cuda-c-and-c

sdl/plot2d.c

@@ -1,6 +1,15 @@
 /*
 Plot 2D function of time.
 
+TODO possible to do it faster? Just the loop without anything inside
+and only FPS calculation and no optimization max out at 70 FPS already.
+Look into surfaces, textures.
+
+- http://stackoverflow.com/questions/20753726/rendering-pixels-from-array-of-rgb-values-in-sdl-1-2
+- http://stackoverflow.com/questions/28279242/how-to-render-a-pixel-array-most-efficiently-to-a-window-in-c
+- http://stackoverflow.com/questions/20348616/how-to-create-a-color-gradient-in-sdl
+- http://stackoverflow.com/questions/21392755/difference-between-surface-and-texture-sdl-general
+
 TODO: get vsync right.
 */