Add wasm

pre.js

+/**
+ *  Replace Moudle['quit'] to avoid process.exit();
+ *
+ *  @ref: https://github.com/Kagami/ffmpeg.js/blob/v4.2.9003/build/pre.js#L48
+ */
+Module['quit'] = function(status) {
+  if (Module["onExit"]) Module["onExit"](status);
+  throw new ExitStatus(status);
+}
+
+Module['exit'] = exit;
+
+Module["lengthBytesUTF8"] = lengthBytesUTF8;
+Module["stringToUTF8"] = stringToUTF8;
+
+/**
+ * Disable all console output, might need to enable it
+ * for debugging
+ */
+out = err = function() {}

src/wasm/interfaces.cc

+#include <stdio.h>
+#include <stdint.h>
+#include <malloc.h>
+#include "wasm.h"
+
+extern "C" {
+    #include <libavcodec/avcodec.h>
+    #include <libswscale/swscale.h>
+}
+
+int width_ = 0;
+int height_ = 0;
+int framerate_ = 0;
+AVFrame         *frame;
+AVPacket        *packet;
+AVCodecContext  *cc;
+struct SwsContext* swsCtx = NULL;
+
+EM_PORT_API(uint8_t)  encodeInit(int width, int height, int fps) {
+
+    width_ = width;
+    height_ = height;
+    framerate_ = fps;
+
+    const AVCodec *encoder = avcodec_find_encoder_by_name("libx264");
+    if (encoder == NULL) {
+        fprintf(stderr, "Unable to find H.264 decoder\n");
+        return 1;
+    }
+    cc = avcodec_alloc_context3(encoder);
+    if (cc == NULL) {
+        fprintf(stderr, "Unable to alloc codec context\n");
+        return 2;
+    }
+
+    // Setup encode parameters
+    cc->width = width;
+    cc->height = height;
+    cc->pix_fmt = AV_PIX_FMT_YUV420P;
+    cc->time_base = (AVRational){1, 90000};
+
+    if (avcodec_open2(cc, encoder, NULL) < 0) {
+        fprintf(stderr, "Unable to open codec context\n");
+        return 3;
+    }
+
+    packet = av_packet_alloc();
+    if (packet == NULL) {
+        fprintf(stderr, "Could not allocate packet\n");
+    }
+
+    frame = av_frame_alloc();
+    frame->format = cc->pix_fmt;
+    frame->width = cc->width;
+    frame->height = cc->height;
+    int ret = av_frame_get_buffer(frame, 0);
+    if (ret < 0) {
+        fprintf(stderr, "Could not allocate the video frame data\n");
+        return 4;
+    }
+
+    swsCtx = sws_getCachedContext(swsCtx, width, height, AV_PIX_FMT_RGBA,
+        width, height, AV_PIX_FMT_YUV420P,
+        SWS_BICUBIC,
+        NULL, NULL, NULL);
+
+
+    return 0;
+}
+
+EM_PORT_API(uint8_t*) encode(uint8_t *data, uint32_t *size) {
+    int ret = 0;
+    uint8_t *mem;
+
+    if (av_frame_make_writable(frame) < 0) {
+        fprintf(stderr, "Fail to make frame writable\n");
+    }
+
+    AVFrame *rgbaFrame = av_frame_alloc();
+    rgbaFrame->format =AV_PIX_FMT_RGBA;
+    rgbaFrame->height = cc->height;
+    rgbaFrame->width = cc->width;
+    avpicture_fill((AVPicture*)rgbaFrame, data, AV_PIX_FMT_RGBA, width_, height_);
+
+    //转换的YUV数据存放在frame
+    int outSliceH = sws_scale(swsCtx, (const uint8_t* const*)rgbaFrame->data, rgbaFrame->linesize, 0, height_,
+        frame->data, frame->linesize);
+
+    if (outSliceH <= 0) {
+        printf("outSliceH <= 0 \n");
+        return NULL;
+    }
+
+    frame->pts = AV_NOPTS_VALUE;
+    frame->pict_type = AV_PICTURE_TYPE_I;
+
+    // Encode
+    ret = avcodec_send_frame(cc, frame);
+    if (ret < 0) {
+        fprintf(stderr, "Fail to encoding\n");
+    }
+    while (true) {
+        ret = avcodec_receive_packet(cc, packet);
+        if (ret) break;
+
+        // For video frame avcodec_receive_packet should return
+        // only once.
+        mem = (uint8_t*)malloc(packet->size);
+        memcpy(mem, packet->data, packet->size);
+    }
+
+    av_packet_unref(packet);
+    av_frame_unref(frame);
+
+    *size = packet->size;
+    return mem;
+}
+
+
+// Trivial main
+int main(int argc, char *argv[]) {}

src/wasm/wasm.h

+#ifndef EM_PORT_API
+#if defined(__EMSCRIPTEN__)
+#include <emscripten.h>
+#if defined(__cplusplus)
+#define EM_PORT_API(rettype) extern "C" rettype EMSCRIPTEN_KEEPALIVE
+#else
+#define EM_PORT_API(rettype) rettype EMSCRIPTEN_KEEPALIVE
+#endif
+#else
+#if defined(__cplusplus)
+#define EM_PORT_API(rettype) extern "C" rettype
+#else
+#define EM_PORT_API(rettype) rettype
+#endif
+#endif
+#endif

wasm-build.sh

+#!/bin/bash
+
+#set -eo pipefail
+
+WORKPATH=$(cd $(dirname $0); pwd)
+
+DEMO_PATH=$WORKPATH/src
+
+echo "WORKPATH"=$WORKPATH
+
+rm -rf ${DEMO_PATH}/mp4encoder.js ${DEMO_PATH}/mp4encoder.wasm
+
+FFMPEG_ST=yes
+
+EMSDK=/emsdk
+
+THIRD_DIR=${WORKPATH}/lib/third/build
+WASM_DIR=${WORKPATH}/src/wasm
+
+DEBUG="-O3"
+#DEBUG="-O1 -g -fno-inline -gseparate-dwarf=/code/demo2/temp.debug.wasm -s SEPARATE_DWARF_URL=http://localhost:5000/temp.debug.wasm"
+
+#--closure 压缩胶水代码，有可能会造成变量重复定义。生产发布可设为1
+OPTIM_FLAGS="$DEBUG --closure 0"
+
+if [[ "$FFMPEG_ST" != "yes" ]]; then
+  EXTRA_FLAGS=(
+    -pthread
+    -s USE_PTHREADS=1                             # enable pthreads support
+    -s PROXY_TO_PTHREAD=1                         # detach main() from browser/UI main thread
+    -o ${DEMO_PATH}/mp4encoder.js
+  )
+else
+  EXTRA_FLAGS=(
+    -o ${DEMO_PATH}/mp4encoder.js
+  )
+fi
+
+FLAGS=(
+  -I$WORKPATH/lib/ffmpeg-emcc/include -L$WORKPATH/lib/ffmpeg-emcc/lib -I$THIRD_DIR/include -L$THIRD_DIR/lib
+  -Wno-deprecated-declarations -Wno-pointer-sign -Wno-implicit-int-float-conversion -Wno-switch -Wno-parentheses -Qunused-arguments
+  -lavdevice -lavfilter -lavformat -lavcodec -lswresample -lswscale -lavutil -lpostproc
+  -lm -lharfbuzz -lfribidi -lass -lx264 -lx265 -lvpx -lwavpack -lmp3lame -lfdk-aac -lvorbis -lvorbisenc -lvorbisfile -logg -ltheora -ltheoraenc -ltheoradec -lz -lfreetype -lopus -lwebp
+  $WASM_DIR/interfaces.cc  $WASM_DIR/utils.cc
+
+  -s FORCE_FILESYSTEM=1
+  -s ENVIRONMENT='web'
+  -s WASM=1
+  #-s USE_SDL=0                                  # use SDL2
+  -s INVOKE_RUN=0                               # not to run the main() in the beginning
+  -s EXIT_RUNTIME=1                             # exit runtime after execution
+  -s MODULARIZE=1                               # 延迟加载 use modularized version to be more flexible
+  -s EXPORT_NAME="createMP4Encoder"             # assign export name for browser
+  -s EXPORTED_FUNCTIONS="[_main,_malloc,_free]"  # export main and proxy_main funcs
+  -s EXPORTED_RUNTIME_METHODS="[FS, cwrap, ccall, setValue, writeAsciiToMemory, getValue]"   # export preamble funcs
+  -s INITIAL_MEMORY=268435456                   # 64 KB * 1024 * 16 * 2047 = 2146435072 bytes ~= 2 GB,   268435456 =256M, 134,217,728 =128M
+  -s ALLOW_MEMORY_GROWTH=1
+  -s ASSERTIONS=1
+  --pre-js $WORKPATH/pre.js
+  --post-js $WORKPATH/post.js
+  $OPTIM_FLAGS
+  ${EXTRA_FLAGS[@]}
+)
+
+emcc "${FLAGS[@]}"
+
+mv  ${DEMO_PATH}/mp4encoder.wasm tmp/mp4encoder.wasm