我正在使用FFmpegFrameRecorder从我的网络摄像头获取视频输入并将其录制到视频文件中。问题是我正在使用我发现的几个不同的演示源代码来构建我的应用程序，并且我使用的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();
(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？最后，我只想提一下我记录这样的视频的最后一个问题。如果视频的实际长度让我们说20秒。当我播放从该程序创建的视频文件时，它运行得更快。无法判断它是否比它应该快2倍，但总的来说，如果我录制20秒的视频，那么它的播放时间大约为10秒。可能导致这种情况的原因以及如何解决？
答案 0 :(得分：22)
avcodec.h / avcodec.java中找到的此列表中选择VideoCodec （正如您所看到的，数字13使我们获得MPEG4，还有其他人，但是FFmpeg没有所有这些编码器）：
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
pixfmt.h / avutil.java中的此列表中选择 PixelFormat ，但每个编解码器仅支持其中一些（大多数支持至少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 表示视频应该在每秒播放的帧数（它与您实际录制的图像的数量或时间无关，尽管它提供了一个基础。编码比特率）。因此，在30 FPS的情况下，要覆盖20秒的视频，您需要拨打record() 30 * 20 = 600次。如果你没有拨打record() 600次，那么这就是问题的原因。
VideoBitrate 提供应在其中编码视频流的视频比特率（以每秒位数为单位）。维基百科有a nice article about that。