ffmpeg - 需要 JavaCV FFmpegFrameRecorder 属性解释

Question

我正在使用 FFmpegFrameRecorder 从网络摄像头获取视频输入并将其记录到视频文件中。问题是我正在使用我发现的一些不同的演示源代码构建我的应用程序，并且我使用其中一些属性对我来说并不完全清楚。

首先，这是我的代码片段:

FFmpegFrameRecorder recorder = new FFmpegFrameRecorder(FILENAME,  grabber.getImageWidth(),grabber.getImageHeight());

        recorder.setVideoCodec(13);
        recorder.setFormat("mp4");
        recorder.setPixelFormat(avutil.PIX_FMT_YUV420P);
        recorder.setFrameRate(30);
        recorder.setVideoBitrate(10 * 1024 * 1024);

        recorder.start();

• setVideoCodec(13) - 此 (13) 的含义是什么，我如何理解任何数字背后的实际编解码器？
• setPixelFormat - 只是得到这个，不知道它一般在做什么
• setFrameRate(30) - 我认为这应该很清楚，但我们选择帧速率背后的逻辑是什么(不是越高越好吗？)
• setVideoBitrate(10*1024*1024) - 再次几乎不知道它的作用以及数字背后的逻辑是什么？

最后我只想提最后一个问题，我像这样录制视频。如果视频的实际长度是 20 秒。当我播放从该程序创建的视频文件时，它的运行速度明显加快。无法判断它是否比应有的速度快 2 倍，但一般来说，如果我录制 20 秒的视频，那么它会播放大约 10 秒。什么可能导致此问题以及如何解决它？

Answer 1

VideoCodec 可以从 avcodec.h/avcodec.java 中找到的列表中选择(如您所见，数字 13 为我们 MPEG4，还有其他的，但 FFmpeg 没有所有这些的编码器):

    AV_CODEC_ID_MPEG1VIDEO = 1,
    /** preferred ID for MPEG-1/2 video decoding */
    AV_CODEC_ID_MPEG2VIDEO = 2,
    AV_CODEC_ID_MPEG2VIDEO_XVMC = 3,
    AV_CODEC_ID_H261 = 4,
    AV_CODEC_ID_H263 = 5,
    AV_CODEC_ID_RV10 = 6,
    AV_CODEC_ID_RV20 = 7,
    AV_CODEC_ID_MJPEG = 8,
    AV_CODEC_ID_MJPEGB = 9,
    AV_CODEC_ID_LJPEG = 10,
    AV_CODEC_ID_SP5X = 11,
    AV_CODEC_ID_JPEGLS = 12,
    AV_CODEC_ID_MPEG4 = 13,
    AV_CODEC_ID_RAWVIDEO = 14,
    AV_CODEC_ID_MSMPEG4V1 = 15,
    AV_CODEC_ID_MSMPEG4V2 = 16,
    AV_CODEC_ID_MSMPEG4V3 = 17,
    AV_CODEC_ID_WMV1 = 18,
    AV_CODEC_ID_WMV2 = 19,
    AV_CODEC_ID_H263P = 20,
    AV_CODEC_ID_H263I = 21,
    AV_CODEC_ID_FLV1 = 22,
    AV_CODEC_ID_SVQ1 = 23,
    AV_CODEC_ID_SVQ3 = 24,
    AV_CODEC_ID_DVVIDEO = 25,
    AV_CODEC_ID_HUFFYUV = 26,
    AV_CODEC_ID_CYUV = 27,
    AV_CODEC_ID_H264 = 28,
    AV_CODEC_ID_INDEO3 = 29,
    AV_CODEC_ID_VP3 = 30,
    AV_CODEC_ID_THEORA = 31,
    AV_CODEC_ID_ASV1 = 32,
    AV_CODEC_ID_ASV2 = 33,
    AV_CODEC_ID_FFV1 = 34,
    AV_CODEC_ID_4XM = 35,
    AV_CODEC_ID_VCR1 = 36,
    AV_CODEC_ID_CLJR = 37,
    AV_CODEC_ID_MDEC = 38,
    AV_CODEC_ID_ROQ = 39,
    AV_CODEC_ID_INTERPLAY_VIDEO = 40,
    AV_CODEC_ID_XAN_WC3 = 41,
    AV_CODEC_ID_XAN_WC4 = 42,
    AV_CODEC_ID_RPZA = 43,
    AV_CODEC_ID_CINEPAK = 44,
    AV_CODEC_ID_WS_VQA = 45,
    AV_CODEC_ID_MSRLE = 46,
    AV_CODEC_ID_MSVIDEO1 = 47,
    AV_CODEC_ID_IDCIN = 48,
    AV_CODEC_ID_8BPS = 49,
    AV_CODEC_ID_SMC = 50,
    AV_CODEC_ID_FLIC = 51,
    AV_CODEC_ID_TRUEMOTION1 = 52,
    AV_CODEC_ID_VMDVIDEO = 53,
    AV_CODEC_ID_MSZH = 54,
    AV_CODEC_ID_ZLIB = 55,
    AV_CODEC_ID_QTRLE = 56,
    AV_CODEC_ID_TSCC = 57,
    AV_CODEC_ID_ULTI = 58,
    AV_CODEC_ID_QDRAW = 59,
    AV_CODEC_ID_VIXL = 60,
    AV_CODEC_ID_QPEG = 61,
    AV_CODEC_ID_PNG = 62,
    AV_CODEC_ID_PPM = 63,
    AV_CODEC_ID_PBM = 64,
    AV_CODEC_ID_PGM = 65,
    AV_CODEC_ID_PGMYUV = 66,
    AV_CODEC_ID_PAM = 67,
    AV_CODEC_ID_FFVHUFF = 68,
    AV_CODEC_ID_RV30 = 69,
    AV_CODEC_ID_RV40 = 70,
    AV_CODEC_ID_VC1 = 71,
    AV_CODEC_ID_WMV3 = 72,
    AV_CODEC_ID_LOCO = 73,
    AV_CODEC_ID_WNV1 = 74,
    AV_CODEC_ID_AASC = 75,
    AV_CODEC_ID_INDEO2 = 76,
    AV_CODEC_ID_FRAPS = 77,
    AV_CODEC_ID_TRUEMOTION2 = 78,
    AV_CODEC_ID_BMP = 79,
    AV_CODEC_ID_CSCD = 80,
    AV_CODEC_ID_MMVIDEO = 81,
    AV_CODEC_ID_ZMBV = 82,
    AV_CODEC_ID_AVS = 83,
    AV_CODEC_ID_SMACKVIDEO = 84,
    AV_CODEC_ID_NUV = 85,
    AV_CODEC_ID_KMVC = 86,
    AV_CODEC_ID_FLASHSV = 87,
    AV_CODEC_ID_CAVS = 88,
    AV_CODEC_ID_JPEG2000 = 89,
    AV_CODEC_ID_VMNC = 90,
    AV_CODEC_ID_VP5 = 91,
    AV_CODEC_ID_VP6 = 92,
    AV_CODEC_ID_VP6F = 93,
    AV_CODEC_ID_TARGA = 94,
    AV_CODEC_ID_DSICINVIDEO = 95,
    AV_CODEC_ID_TIERTEXSEQVIDEO = 96,
    AV_CODEC_ID_TIFF = 97,
    AV_CODEC_ID_GIF = 98,
    AV_CODEC_ID_DXA = 99,
    AV_CODEC_ID_DNXHD = 100,
    AV_CODEC_ID_THP = 101,
    AV_CODEC_ID_SGI = 102,
    AV_CODEC_ID_C93 = 103,
    AV_CODEC_ID_BETHSOFTVID = 104,
    AV_CODEC_ID_PTX = 105,
    AV_CODEC_ID_TXD = 106,
    AV_CODEC_ID_VP6A = 107,
    AV_CODEC_ID_AMV = 108,
    AV_CODEC_ID_VB = 109,
    AV_CODEC_ID_PCX = 110,
    AV_CODEC_ID_SUNRAST = 111,
    AV_CODEC_ID_INDEO4 = 112,
    AV_CODEC_ID_INDEO5 = 113,
    AV_CODEC_ID_MIMIC = 114,
    AV_CODEC_ID_RL2 = 115,
    AV_CODEC_ID_ESCAPE124 = 116,
    AV_CODEC_ID_DIRAC = 117,
    AV_CODEC_ID_BFI = 118,
    AV_CODEC_ID_CMV = 119,
    AV_CODEC_ID_MOTIONPIXELS = 120,
    AV_CODEC_ID_TGV = 121,
    AV_CODEC_ID_TGQ = 122,
    AV_CODEC_ID_TQI = 123,
    AV_CODEC_ID_AURA = 124,
    AV_CODEC_ID_AURA2 = 125,
    AV_CODEC_ID_V210X = 126,
    AV_CODEC_ID_TMV = 127,
    AV_CODEC_ID_V210 = 128,
    AV_CODEC_ID_DPX = 129,
    AV_CODEC_ID_MAD = 130,
    AV_CODEC_ID_FRWU = 131,
    AV_CODEC_ID_FLASHSV2 = 132,
    AV_CODEC_ID_CDGRAPHICS = 133,
    AV_CODEC_ID_R210 = 134,
    AV_CODEC_ID_ANM = 135,
    AV_CODEC_ID_BINKVIDEO = 136,
    AV_CODEC_ID_IFF_ILBM = 137,
    AV_CODEC_ID_IFF_BYTERUN1 = 138,
    AV_CODEC_ID_KGV1 = 139,
    AV_CODEC_ID_YOP = 140,
    AV_CODEC_ID_VP8 = 141,
    AV_CODEC_ID_PICTOR = 142,
    AV_CODEC_ID_ANSI = 143,
    AV_CODEC_ID_A64_MULTI = 144,
    AV_CODEC_ID_A64_MULTI5 = 145,
    AV_CODEC_ID_R10K = 146,
    AV_CODEC_ID_MXPEG = 147,
    AV_CODEC_ID_LAGARITH = 148,
    AV_CODEC_ID_PRORES = 149,
    AV_CODEC_ID_JV = 150,
    AV_CODEC_ID_DFA = 151,
    AV_CODEC_ID_WMV3IMAGE = 152,
    AV_CODEC_ID_VC1IMAGE = 153,
    AV_CODEC_ID_UTVIDEO = 154,
    AV_CODEC_ID_BMV_VIDEO = 155,
    AV_CODEC_ID_VBLE = 156,
    AV_CODEC_ID_DXTORY = 157,
    AV_CODEC_ID_V410 = 158,
    AV_CODEC_ID_XWD = 159,
    AV_CODEC_ID_CDXL = 160,
    AV_CODEC_ID_XBM = 161,
    AV_CODEC_ID_ZEROCODEC = 162,
    AV_CODEC_ID_MSS1 = 163,
    AV_CODEC_ID_MSA1 = 164,
    AV_CODEC_ID_TSCC2 = 165,
    AV_CODEC_ID_MTS2 = 166,
    AV_CODEC_ID_CLLC = 167,
    AV_CODEC_ID_MSS2 = 168,
    AV_CODEC_ID_VP9 = 169,
    AV_CODEC_ID_AIC = 170,
    // etc

PixelFormat 可以从 pixfmt.h/avutil.java 中的此列表中选择，但每个编解码器仅支持其中的几种(其中大多数至少支持AV_PIX_FMT_YUV420P):

    /** planar YUV 4:2:0, 12bpp, (1 Cr & Cb sample per 2x2 Y samples) */
    AV_PIX_FMT_YUV420P = 0,
    /** packed YUV 4:2:2, 16bpp, Y0 Cb Y1 Cr */
    AV_PIX_FMT_YUYV422 = 1,
    /** packed RGB 8:8:8, 24bpp, RGBRGB... */
    AV_PIX_FMT_RGB24 = 2,
    /** packed RGB 8:8:8, 24bpp, BGRBGR... */
    AV_PIX_FMT_BGR24 = 3,
    /** planar YUV 4:2:2, 16bpp, (1 Cr & Cb sample per 2x1 Y samples) */
    AV_PIX_FMT_YUV422P = 4,
    /** planar YUV 4:4:4, 24bpp, (1 Cr & Cb sample per 1x1 Y samples) */
    AV_PIX_FMT_YUV444P = 5,
    /** planar YUV 4:1:0,  9bpp, (1 Cr & Cb sample per 4x4 Y samples) */
    AV_PIX_FMT_YUV410P = 6,
    /** planar YUV 4:1:1, 12bpp, (1 Cr & Cb sample per 4x1 Y samples) */
    AV_PIX_FMT_YUV411P = 7,
    /**        Y        ,  8bpp */
    AV_PIX_FMT_GRAY8 = 8,
    /**        Y        ,  1bpp, 0 is white, 1 is black, in each byte pixels are ordered from the msb to the lsb */
    AV_PIX_FMT_MONOWHITE = 9,
    /**        Y        ,  1bpp, 0 is black, 1 is white, in each byte pixels are ordered from the msb to the lsb */
    AV_PIX_FMT_MONOBLACK = 10,
    /** 8 bit with PIX_FMT_RGB32 palette */
    AV_PIX_FMT_PAL8 = 11,
    /** planar YUV 4:2:0, 12bpp, full scale (JPEG), deprecated in favor of PIX_FMT_YUV420P and setting color_range */
    AV_PIX_FMT_YUVJ420P = 12,
    /** planar YUV 4:2:2, 16bpp, full scale (JPEG), deprecated in favor of PIX_FMT_YUV422P and setting color_range */
    AV_PIX_FMT_YUVJ422P = 13,
    /** planar YUV 4:4:4, 24bpp, full scale (JPEG), deprecated in favor of PIX_FMT_YUV444P and setting color_range */
    AV_PIX_FMT_YUVJ444P = 14,
    /** XVideo Motion Acceleration via common packet passing */
    AV_PIX_FMT_XVMC_MPEG2_MC = 15,
    AV_PIX_FMT_XVMC_MPEG2_IDCT = 16;
    /** packed YUV 4:2:2, 16bpp, Cb Y0 Cr Y1 */
    AV_PIX_FMT_UYVY422 = 17,
    /** packed YUV 4:1:1, 12bpp, Cb Y0 Y1 Cr Y2 Y3 */
    AV_PIX_FMT_UYYVYY411 = 18,
    /** packed RGB 3:3:2,  8bpp, (msb)2B 3G 3R(lsb) */
    AV_PIX_FMT_BGR8 = 19,
    /** packed RGB 1:2:1 bitstream,  4bpp, (msb)1B 2G 1R(lsb), a byte contains two pixels, the first pixel in the byte is the one composed by the 4 msb bits */
    AV_PIX_FMT_BGR4 = 20,
    /** packed RGB 1:2:1,  8bpp, (msb)1B 2G 1R(lsb) */
    AV_PIX_FMT_BGR4_BYTE = 21,
    /** packed RGB 3:3:2,  8bpp, (msb)2R 3G 3B(lsb) */
    AV_PIX_FMT_RGB8 = 22,
    /** packed RGB 1:2:1 bitstream,  4bpp, (msb)1R 2G 1B(lsb), a byte contains two pixels, the first pixel in the byte is the one composed by the 4 msb bits */
    AV_PIX_FMT_RGB4 = 23,
    /** packed RGB 1:2:1,  8bpp, (msb)1R 2G 1B(lsb) */
    AV_PIX_FMT_RGB4_BYTE = 24,
    /** planar YUV 4:2:0, 12bpp, 1 plane for Y and 1 plane for the UV components, which are interleaved (first byte U and the following byte V) */
    AV_PIX_FMT_NV12 = 25,
    /** as above, but U and V bytes are swapped */
    AV_PIX_FMT_NV21 = 26,

    /** packed ARGB 8:8:8:8, 32bpp, ARGBARGB... */
    AV_PIX_FMT_ARGB = 27,
    /** packed RGBA 8:8:8:8, 32bpp, RGBARGBA... */
    AV_PIX_FMT_RGBA = 28,
    /** packed ABGR 8:8:8:8, 32bpp, ABGRABGR... */
    AV_PIX_FMT_ABGR = 29,
    /** packed BGRA 8:8:8:8, 32bpp, BGRABGRA... */
    AV_PIX_FMT_BGRA = 30,

    /**        Y        , 16bpp, big-endian */
    AV_PIX_FMT_GRAY16BE = 31,
    /**        Y        , 16bpp, little-endian */
    AV_PIX_FMT_GRAY16LE = 32,
    /** planar YUV 4:4:0 (1 Cr & Cb sample per 1x2 Y samples) */
    AV_PIX_FMT_YUV440P = 33,
    /** planar YUV 4:4:0 full scale (JPEG), deprecated in favor of PIX_FMT_YUV440P and setting color_range */
    AV_PIX_FMT_YUVJ440P = 34,
    /** planar YUV 4:2:0, 20bpp, (1 Cr & Cb sample per 2x2 Y & A samples) */
    AV_PIX_FMT_YUVA420P = 35,
    /** H.264 HW decoding with VDPAU, data[0] contains a vdpau_render_state struct which contains the bitstream of the slices as well as various fields extracted from headers */
    AV_PIX_FMT_VDPAU_H264 = 36,
    /** MPEG-1 HW decoding with VDPAU, data[0] contains a vdpau_render_state struct which contains the bitstream of the slices as well as various fields extracted from headers */
    AV_PIX_FMT_VDPAU_MPEG1 = 37,
    /** MPEG-2 HW decoding with VDPAU, data[0] contains a vdpau_render_state struct which contains the bitstream of the slices as well as various fields extracted from headers */
    AV_PIX_FMT_VDPAU_MPEG2 = 38,
    /** WMV3 HW decoding with VDPAU, data[0] contains a vdpau_render_state struct which contains the bitstream of the slices as well as various fields extracted from headers */
    AV_PIX_FMT_VDPAU_WMV3 = 39,
    /** VC-1 HW decoding with VDPAU, data[0] contains a vdpau_render_state struct which contains the bitstream of the slices as well as various fields extracted from headers */
    AV_PIX_FMT_VDPAU_VC1 = 40,
    /** packed RGB 16:16:16, 48bpp, 16R, 16G, 16B, the 2-byte value for each R/G/B component is stored as big-endian */
    AV_PIX_FMT_RGB48BE = 41,
    /** packed RGB 16:16:16, 48bpp, 16R, 16G, 16B, the 2-byte value for each R/G/B component is stored as little-endian */
    AV_PIX_FMT_RGB48LE = 42,

    /** packed RGB 5:6:5, 16bpp, (msb)   5R 6G 5B(lsb), big-endian */
    AV_PIX_FMT_RGB565BE = 43,
    /** packed RGB 5:6:5, 16bpp, (msb)   5R 6G 5B(lsb), little-endian */
    AV_PIX_FMT_RGB565LE = 44,
    /** packed RGB 5:5:5, 16bpp, (msb)1A 5R 5G 5B(lsb), big-endian, most significant bit to 0 */
    AV_PIX_FMT_RGB555BE = 45,
    /** packed RGB 5:5:5, 16bpp, (msb)1A 5R 5G 5B(lsb), little-endian, most significant bit to 0 */
    AV_PIX_FMT_RGB555LE = 46,

    /** packed BGR 5:6:5, 16bpp, (msb)   5B 6G 5R(lsb), big-endian */
    AV_PIX_FMT_BGR565BE = 47,
    /** packed BGR 5:6:5, 16bpp, (msb)   5B 6G 5R(lsb), little-endian */
    AV_PIX_FMT_BGR565LE = 48,
    /** packed BGR 5:5:5, 16bpp, (msb)1A 5B 5G 5R(lsb), big-endian, most significant bit to 1 */
    AV_PIX_FMT_BGR555BE = 49,
    /** packed BGR 5:5:5, 16bpp, (msb)1A 5B 5G 5R(lsb), little-endian, most significant bit to 1 */
    AV_PIX_FMT_BGR555LE = 50,

    /** HW acceleration through VA API at motion compensation entry-point, Picture.data[3] contains a vaapi_render_state struct which contains macroblocks as well as various fields extracted from headers */
    AV_PIX_FMT_VAAPI_MOCO = 51,
    /** HW acceleration through VA API at IDCT entry-point, Picture.data[3] contains a vaapi_render_state struct which contains fields extracted from headers */
    AV_PIX_FMT_VAAPI_IDCT = 52,
    /** HW decoding through VA API, Picture.data[3] contains a vaapi_render_state struct which contains the bitstream of the slices as well as various fields extracted from headers */
    AV_PIX_FMT_VAAPI_VLD = 53,

    /** planar YUV 4:2:0, 24bpp, (1 Cr & Cb sample per 2x2 Y samples), little-endian */
    AV_PIX_FMT_YUV420P16LE = 54,
    /** planar YUV 4:2:0, 24bpp, (1 Cr & Cb sample per 2x2 Y samples), big-endian */
    AV_PIX_FMT_YUV420P16BE = 55,
    /** planar YUV 4:2:2, 32bpp, (1 Cr & Cb sample per 2x1 Y samples), little-endian */
    AV_PIX_FMT_YUV422P16LE = 56,
    /** planar YUV 4:2:2, 32bpp, (1 Cr & Cb sample per 2x1 Y samples), big-endian */
    AV_PIX_FMT_YUV422P16BE = 57,
    /** planar YUV 4:4:4, 48bpp, (1 Cr & Cb sample per 1x1 Y samples), little-endian */
    AV_PIX_FMT_YUV444P16LE = 58,
    /** planar YUV 4:4:4, 48bpp, (1 Cr & Cb sample per 1x1 Y samples), big-endian */
    AV_PIX_FMT_YUV444P16BE = 59,
    /** MPEG4 HW decoding with VDPAU, data[0] contains a vdpau_render_state struct which contains the bitstream of the slices as well as various fields extracted from headers */
    AV_PIX_FMT_VDPAU_MPEG4 = 60,
    /** HW decoding through DXVA2, Picture.data[3] contains a LPDIRECT3DSURFACE9 pointer */
    AV_PIX_FMT_DXVA2_VLD = 61,

    /** packed RGB 4:4:4, 16bpp, (msb)4A 4R 4G 4B(lsb), little-endian, most significant bits to 0 */
    AV_PIX_FMT_RGB444LE = 62,
    /** packed RGB 4:4:4, 16bpp, (msb)4A 4R 4G 4B(lsb), big-endian, most significant bits to 0 */
    AV_PIX_FMT_RGB444BE = 63,
    /** packed BGR 4:4:4, 16bpp, (msb)4A 4B 4G 4R(lsb), little-endian, most significant bits to 1 */
    AV_PIX_FMT_BGR444LE = 64,
    /** packed BGR 4:4:4, 16bpp, (msb)4A 4B 4G 4R(lsb), big-endian, most significant bits to 1 */
    AV_PIX_FMT_BGR444BE = 65,
    /** 8bit gray, 8bit alpha */
    AV_PIX_FMT_YA8 = 66,
    // etc

FrameRate表示视频应播放的每秒帧数(它与您实际录制的图像数量或时间无关，尽管它为编码比特率)。因此，在 30 FPS 的情况下，要覆盖 20 秒的视频，需要调用 record() 30 * 20 = 600 次。如果您没有调用 record() 600 次，那么这就是问题的原因。

VideoBitrate 提供视频流编码的视频比特率(以每秒位数为单位)。维基百科有a nice article about that .