我正在尝试使用 MediaCodec 和 MediaMuxer 将一系列 JPEG 转换为 mp4。
无论我做什么，我总是在 MP4 上得到一个绿色的静态屏幕作为输出。
代码如下：
public class AvcEncoder
{
public bool CanEncode = true;
MediaCodec codec;
MediaMuxer muxer;
MediaFormat format;
public AvcEncoder()
{
codec = MediaCodec.CreateEncoderByType("video/avc");
format = MediaFormat.CreateVideoFormat("video/avc", 720, 480);
format.SetInteger(MediaFormat.KeyBitRate, 700000);
format.SetInteger(MediaFormat.KeyFrameRate, 10);
format.SetInteger(MediaFormat.KeyColorFormat, (int)Android.Media.MediaCodecCapabilities.Formatyuv420planar);
format.SetInteger(MediaFormat.KeyIFrameInterval, 5);
codec.Configure(format, null, null, MediaCodecConfigFlags.Encode);
codec.Start();
Java.IO.File f = new Java.IO.File(Android.OS.Environment.ExternalStorageDirectory, "Parkingdom");
if (!f.Exists())
{
f.Mkdirs();
}
muxer = new MediaMuxer(f.ToString() + "/test.mp4", MuxerOutputType.Mpeg4);
}
public void EncodeFrame(Bitmap image)
{
int mWidth = image.Width;
int mHeight = image.Height;
int[] mIntArray = new int[mWidth * mHeight];
// Copy pixel data from the Bitmap into the 'intArray' array
image.GetPixels(mIntArray, 0, mWidth, 0, 0, mWidth, mHeight);
byte[] byteArray = new byte[mWidth * mHeight * 3 / 2];
// Call to encoding function : convert intArray to Yuv Binary data
EncodeYUV420P(byteArray, mIntArray, mWidth, mHeight);
using (var stream = new MemoryStream())
{
image.Compress(Bitmap.CompressFormat.Png, 100, stream);
byteArray = stream.ToArray();
}
int inputBufferIndex = codec.DequeueInputBuffer(-1);
if (inputBufferIndex >= 0)
{
ByteBuffer buffer = codec.GetInputBuffer(inputBufferIndex);
buffer.Clear();
buffer.Put(byteArray);
codec.QueueInputBuffer(inputBufferIndex, 0, byteArray.Length, 0, 0);
}
}
public void SaveMp4()
{
CanEncode = false;
bool running = true;
MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();
int track = -1;
while (running)
{
int index = codec.DequeueOutputBuffer(bufferInfo, 10000);
if (index == (int)MediaCodecInfoState.OutputFormatChanged)
{
MediaFormat format = codec.OutputFormat;
track = muxer.AddTrack(format);
muxer.Start();
}
else if (index == (int)MediaCodecInfoState.TryAgainLater)
{
break;
}
else if (index >= 0)
{
if ((bufferInfo.Flags & MediaCodecBufferFlags.CodecConfig) != 0)
{
bufferInfo.Size = 0;
}
if (track != -1)
{
ByteBuffer outBuffer = codec.GetOutputBuffer(index);
outBuffer.Position(bufferInfo.Offset);
outBuffer.Limit(bufferInfo.Offset + bufferInfo.Size);
muxer.WriteSampleData(track, outBuffer, bufferInfo);
codec.ReleaseOutputBuffer(index, false);
}
}
}
codec.Stop();
codec.Release();
muxer.Stop();
muxer.Release();
CanEncode = true;
}
void EncodeYUV420P(byte[] yuv420p, int[] argb, int width, int height)
{
int frameSize = width * height;
int chromasize = frameSize / 4;
int yIndex = 0;
int uIndex = frameSize;
int vIndex = frameSize + chromasize;
int a, R, G, B, Y, U, V;
int index = 0;
for (int j = 0; j < height; j++)
{
for (int i = 0; i < width; i++)
{
a = (int)(argb[index] & 0xff000000) >> 24; // a is not used obviously
R = (argb[index] & 0xff0000) >> 16;
G = (argb[index] & 0xff00) >> 8;
B = (argb[index] & 0xff) >> 0;
Y = ((66 * R + 129 * G + 25 * B + 128) >> 8) + 16;
U = ((-38 * R - 74 * G + 112 * B + 128) >> 8) + 128;
V = ((112 * R - 94 * G - 18 * B + 128) >> 8) + 128;
yuv420p[yIndex++] = (byte)((Y < 0) ? 0 : ((Y > 255) ? 255 : Y));
if (j % 2 == 0 && index % 2 == 0)
{
yuv420p[uIndex++] = (byte)((U < 0) ? 0 : ((U > 255) ? 255 : U));
yuv420p[vIndex++] = (byte)((V < 0) ? 0 : ((V > 255) ? 255 : V));
}
index++;
}
}
}
}
每次生成新的 jpeg 时都会调用“EncodeFrame”，这应该将其更改为媒体编解码器的 YUV420Planar 格式。我正在测试的编解码器不支持半平面。