2023-10-22 11:46:19 CST W43D0

examples/avio-reading/main.go

@@ -1,5 +1,118 @@
 package main
 
-func main() {
+/*
+#include <stdlib.h>
 
+int readPacket(void* opaque, uint8_t *buf, int bufSize);
+
+*/
+import "C"
+import (
+	"fmt"
+	"os"
+	"runtime/cgo"
+	"syscall"
+	"unsafe"
+
+	ffmpeg "github.com/qrtc/ffmpeg-dev-go"
+)
+
+type bufferData struct {
+	ptr  *uint8
+	size uintptr
+}
+
+//export readPacket
+func readPacket(opaque unsafe.Pointer, buf *uint8, bufSize int32) int32 {
+	bd := (*(*cgo.Handle)(opaque)).Value().(*bufferData)
+	bufSize = ffmpeg.FFMIN(bufSize, int32(bd.size))
+
+	if bufSize == 0 {
+		return ffmpeg.AVERROR_EOF
+	}
+	fmt.Fprintf(os.Stdout, "ptr:%p size:%d\n", bd.ptr, bd.size)
+
+	// copy internal buffer data to buf
+	bd.ptr = ffmpeg.PointerOffset(bd.ptr, bufSize)
+	bd.size -= uintptr(bufSize)
+
+	return bufSize
+}
+
+func main() {
+	var fmtCtx *ffmpeg.AVFormatContext
+	var avioCtx *ffmpeg.AVIOContext
+	var buffer, avioCtxBuffer *uint8
+	var bufferSize uintptr
+	var avioCtxBufferSize uint = 4096
+	var ret int32
+	var bd bufferData
+	var opaqueHandle cgo.Handle
+
+	if len(os.Args) != 2 {
+		fmt.Fprintf(os.Stderr, "usage: %s input_file\n"+
+			"API example program to show how to read from a custom buffer "+
+			"accessed through AVIOContext.\n", os.Args[0])
+		os.Exit(1)
+	}
+	inputFilename := os.Args[1]
+
+	// slurp file content into buffer
+	if ret = ffmpeg.AvFileMap(inputFilename, &buffer, &bufferSize, 0, nil); ret < 0 {
+		goto end
+	}
+
+	// fill opaque structure used by the AVIOContext read callback
+	bd.ptr = buffer
+	bd.size = bufferSize
+
+	if fmtCtx = ffmpeg.AvFormatAllocContext(); fmtCtx == nil {
+		ret = ffmpeg.AVERROR(syscall.ENOMEM)
+		goto end
+	}
+
+	if avioCtxBuffer = (*uint8)(ffmpeg.AvMalloc(avioCtxBufferSize)); avioCtxBuffer == nil {
+		ret = ffmpeg.AVERROR(syscall.ENOMEM)
+		goto end
+	}
+
+	opaqueHandle = cgo.NewHandle(&bd)
+	if avioCtx = ffmpeg.AvIOAllocContext(avioCtxBuffer, int32(avioCtxBufferSize), 0,
+		&opaqueHandle, (ffmpeg.AVIOContextReadPacketFunc)(C.readPacket), nil, nil); avioCtx == nil {
+		ret = ffmpeg.AVERROR(syscall.ENOMEM)
+		goto end
+	}
+	fmtCtx.SetPb(avioCtx)
+
+	if ret = ffmpeg.AvFormatOpenInput(&fmtCtx, ffmpeg.NIL, nil, nil); ret < 0 {
+		fmt.Fprintf(os.Stderr, "Could not open input\n")
+		goto end
+	}
+
+	if ret = ffmpeg.AvFormatFindStreamInfo(fmtCtx, nil); ret < 0 {
+		fmt.Fprintf(os.Stderr, "Could not find stream information\n")
+		goto end
+	}
+
+	ffmpeg.AvDumpFormat(fmtCtx, 0, inputFilename, 0)
+
+end:
+	ffmpeg.AvFormatCloseInput(&fmtCtx)
+
+	if opaqueHandle != 0 {
+		opaqueHandle.Delete()
+	}
+
+	// note: the internal buffer could have changed, and be != avio_ctx_buffer
+	if avioCtx != nil {
+		ffmpeg.AvFreep(avioCtx.GetBufferAddr())
+	}
+	ffmpeg.AvIOContextFree(&avioCtx)
+
+	ffmpeg.AvFileUnmap(buffer, bufferSize)
+
+	if ret < 0 {
+		fmt.Fprintf(os.Stderr, "Error occurred: %s\n", ffmpeg.AvErr2str(ret))
+		os.Exit(1)
+	}
 }