Question

我正在尝试以下操作来录制来自我的Flash / AIR应用程序的实时视频：

我从每个帧中获取一个“截图”（来自舞台的BitmapData）。

我将每个像素转换为yuv格式，如（V2）：

    var file :File = new File(_appUrl + "/creation/output.raw");
    var fs :FileStream = new FileStream();
    fs.open(file, FileMode.WRITE);
    var finalY :ByteArray = new ByteArray();
    var finalU :ByteArray = new ByteArray();
    var finalV :ByteArray = new ByteArray();
    var rect :Rectangle = new Rectangle(0, 0, 600, 700);
    var pixels :ByteArray;
    var pixel :uint;
    var r :uint;
    var g :uint;
    var b :uint;
    _screenBuffer = _screenBuffer.reverse();
    while (_screenBuffer.length > 0)
    {
        pixels = BitmapData(_screenBuffer.pop()).getPixels(rect);
        pixels.position = 0;
        // Convert and save each pixel
        for (var x:int = 0; x < 600; x++)
        {
            for (var y:int = 0; y < 700; y++)
            {
                // Convert to yuv
                pixel = pixels.readUnsignedInt();
                r = pixel >> 16 & 0xff;
                g = pixel >> 8 & 0xff;
                b = pixel & 0xff;
                    // Y' is written for each pixel
                finalY.writeByte(0.257 * r + 0.504 * g + 0.098 * b + 128);
                    // U and V are written once per 2x2 pixel block
                if (x % 2 == 0 && y % 2 == 0)
                {
                    finalU.writeByte(-0.148 * r - 0.291 * g + 0.439 * b + 128);
                    finalV.writeByte(0.439 * r - 0.368 * g - 0.071 * b + 128);
                }
            }
        }
    }
    // Write the converted bytes to the file
    finalY.position = 0;
    finalU.position = 0;
    finalV.position = 0;
    fs.writeBytes(finalY, 0, finalY.length);
    fs.writeBytes(finalU, 0, finalU.length);
    fs.writeBytes(finalV, 0, finalV.length);
    fs.close();

我使用以下ffmpeg行将原始文件转换为视频：

ffmpeg -r 30 -pix_fmt yuv420p -s 600x700 -vcodec rawvideo -f rawvideo -i output.raw -y test.mp4

视频已创建，但它只是一团糟，几乎与录制的内容完全不同。我知道捕获过程有效，因为我已尝试使用SimpleFlvWriter相同的BitmapData“屏幕截图”。

所以，我的转换或ffmpeg行有问题，但我不知道。

这是ffmpeg在创建视频时输出的内容，也许它可以帮助某人：

libavutil      51. 39.100 / 51. 39.100
libavcodec     54.  3.101 / 54.  3.101
libavformat    54.  1.100 / 54.  1.100
libavdevice    53.  4.100 / 53.  4.100
libavfilter     2. 62.101 /  2. 62.101
libswscale      2.  1.100 /  2.  1.100
libswresample   0.  7.100 /  0.  7.100
libpostproc    52.  0.100 / 52.  0.100
[rawvideo @ 01D39FC0] Estimating duration from bitrate, this may be inaccurate
Input #0, rawvideo, from 'output.raw':
  Duration: N/A, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 600x700, 30 tbr,
30 tbn, 30 tbc
[buffer @ 01D3FEC0] w:600 h:700 pixfmt:yuv420p tb:1/1000000 sar:0/1 sws_param:
[libx264 @ 0375DB80] using cpu capabilities: MMX2 SSE2Fast SSSE3 FastShuffle SSE 4.2 AVX
[libx264 @ 0375DB80] profile High, level 3.1
[libx264 @ 0375DB80] 264 - core 120 r2146 bcd41db - H.264/MPEG-4 AVC codec - Copyleft 2003-2011 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=12 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to 'test.mp4':
  Metadata:
    encoder         : Lavf54.1.100
    Stream #0:0: Video: h264 (![0][0][0] / 0x0021), yuv420p, 600x700, q=-1--1, 30 tbn, 30 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo -> libx264)
Press [q] to stop, [?] for help
Truncating packet of size 630000 to 1
frame=   48 fps=  0 q=-1.0 Lsize=     157kB time=00:00:01.53 bitrate= 837.3kbits/s
video:156kB audio:0kB global headers:0kB muxing overhead 0.687626%
[libx264 @ 0375DB80] frame I:3     Avg QP:23.15  size: 23480
[libx264 @ 0375DB80] frame P:38    Avg QP:28.80  size:  2169
[libx264 @ 0375DB80] frame B:7     Avg QP:29.61  size:   833
[libx264 @ 0375DB80] consecutive B-frames: 79.2%  4.2%  0.0% 16.7%
[libx264 @ 0375DB80] mb I  I16..4: 41.4%  6.2% 52.4%
[libx264 @ 0375DB80] mb P  I16..4: 10.6%  3.3%  0.9%  P16..4: 68.4%  1.3%  1.2% 0.0%  0.0%    skip:14.2%
[libx264 @ 0375DB80] mb B  I16..4:  0.0%  0.0%  0.0%  B16..8: 13.3%  2.2%  0.7% direct: 1.9%  skip:81.9%  L0:51.6% L1:47.4% BI: 1.0%
[libx264 @ 0375DB80] 8x8 transform intra:16.7% inter:31.2%
[libx264 @ 0375DB80] coded y,uvDC,uvAC intra: 14.7% 25.5% 22.3% inter: 1.0% 4.1% 3.4%
[libx264 @ 0375DB80] i16 v,h,dc,p: 87% 11%  2%  0%
[libx264 @ 0375DB80] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu:  3% 18% 75%  1%  0%  1%  1% 0%  0%
[libx264 @ 0375DB80] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu:  6% 74% 12%  1%  1%  1%  2% 1%  2%
[libx264 @ 0375DB80] i8c dc,h,v,p: 51% 45%  4%  1%
[libx264 @ 0375DB80] Weighted P-Frames: Y:0.0% UV:0.0%
[libx264 @ 0375DB80] ref P L0:  4.6%  0.4% 94.6%  0.3%
[libx264 @ 0375DB80] ref B L0: 96.0%  4.0%
[libx264 @ 0375DB80] ref B L1: 96.5%  3.5%
[libx264 @ 0375DB80] kb/s:793.39

我不是真正的编解码器专家（刚开始;）），所以我不知道该怎么做。

Here is a zip包含其中一个帧和视频输出。应该可见的是一个绿色的微笑梨，没有任何文物。请记住，尺寸为600x700，格式为yuv420。最好用irfanview，IMO查看这样的原始图像文件。不要小心噪音，它不要靠在我的麦克风上;）

Answer 1

您使用像素格式

-pix_fmt yuv420p

在内存中

Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 U1234 U5678 V1234 V5678

即每4个像素的正方形有U和一个V.此外，你首先拥有Y，然后是所有U，然后是所有V。

好像你在写

Y1 U1 V1 Y2 U2 V2 ...

有多种像素格式。如果要使用yuv420p，则需要坚持使用内存布局。查看Wikipedia entry on yuv420p

将RGB转换为YUV，+ ffmpeg

1 个答案: