如何用FFmpeg编码灰度视频流？

我有一个来自Firewire天文相机的灰度视频流,我想使用FFmpeg来压缩视频流,但它不接受MPEG1VIDEO编解码器的单字节像素格式.如何使用FFmpeg API将灰度视频帧转换为FFmpeg接受的帧格式？

编辑

MPEG-1只接受YUV.所以将你的帧转换为yuv.使用SwsContext结构,通过调用sws_getContext创建它,然后使用sws_scale.

试试rawvideo编解码器.您需要指定pix_fmt参数来描述帧的格式 - 您的每像素帧为1字节,但它们是否为灰度(您没有提到)？例如

ffmpeg -i INPUT -vcodec rawvideo -pix_fmt yuv420p output.avi

这里pix_fmt指定yuv420p,这不是你需要的.为您使用适当的帧类型.

我将发布pix_fmt值的头文件的内容.尝试查看您的帧类型是否已定义.例如,查看PIX_FMT_RGB8(8位).

/*
 * copyright (c) 2006 Michael Niedermayer 
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#ifndef AVUTIL_PIXFMT_H
#define AVUTIL_PIXFMT_H

/**
 * @file
 * pixel format definitions
 *
 * @warning This file has to be considered an internal but installed
 * header, so it should not be directly included in your projects.
 */

#include "libavutil/avconfig.h"

/**
 * Pixel format. Notes:
 *
 * PIX_FMT_RGB32 is handled in an endian-specific manner. An RGBA
 * color is put together as:
 *  (A << 24) | (R << 16) | (G << 8) | B
 * This is stored as BGRA on little-endian CPU architectures and ARGB on
 * big-endian CPUs.
 *
 * When the pixel format is palettized RGB (PIX_FMT_PAL8), the palettized
 * image data is stored in AVFrame.data[0]. The palette is transported in
 * AVFrame.data[1], is 1024 bytes long (256 4-byte entries) and is
 * formatted the same as in PIX_FMT_RGB32 described above (i.e., it is
 * also endian-specific). Note also that the individual RGB palette
 * components stored in AVFrame.data[1] should be in the range 0..255.
 * This is important as many custom PAL8 video codecs that were designed
 * to run on the IBM VGA graphics adapter use 6-bit palette components.
 *
 * For all the 8bit per pixel formats, an RGB32 palette is in data[1] like
 * for pal8. This palette is filled in automatically by the function
 * allocating the picture.
 *
 * Note, make sure that all newly added big endian formats have pix_fmt&1==1
 *       and that all newly added little endian formats have pix_fmt&1==0
 *       this allows simpler detection of big vs little endian.
 */
enum PixelFormat {
    PIX_FMT_NONE= -1,
    PIX_FMT_YUV420P,   ///< planar YUV 4:2:0, 12bpp, (1 Cr & Cb sample per 2x2 Y samples)
    PIX_FMT_YUYV422,   ///< packed YUV 4:2:2, 16bpp, Y0 Cb Y1 Cr
    PIX_FMT_RGB24,     ///< packed RGB 8:8:8, 24bpp, RGBRGB...
    PIX_FMT_BGR24,     ///< packed RGB 8:8:8, 24bpp, BGRBGR...
    PIX_FMT_YUV422P,   ///< planar YUV 4:2:2, 16bpp, (1 Cr & Cb sample per 2x1 Y samples)
    PIX_FMT_YUV444P,   ///< planar YUV 4:4:4, 24bpp, (1 Cr & Cb sample per 1x1 Y samples)
    PIX_FMT_YUV410P,   ///< planar YUV 4:1:0,  9bpp, (1 Cr & Cb sample per 4x4 Y samples)
    PIX_FMT_YUV411P,   ///< planar YUV 4:1:1, 12bpp, (1 Cr & Cb sample per 4x1 Y samples)
    PIX_FMT_GRAY8,     ///<        Y        ,  8bpp
    PIX_FMT_MONOWHITE, ///<        Y        ,  1bpp, 0 is white, 1 is black, in each byte pixels are ordered from the msb to the lsb
    PIX_FMT_MONOBLACK, ///<        Y        ,  1bpp, 0 is black, 1 is white, in each byte pixels are ordered from the msb to the lsb
    PIX_FMT_PAL8,      ///< 8 bit with PIX_FMT_RGB32 palette
    PIX_FMT_YUVJ420P,  ///< planar YUV 4:2:0, 12bpp, full scale (JPEG), deprecated in favor of PIX_FMT_YUV420P and setting color_range
    PIX_FMT_YUVJ422P,  ///< planar YUV 4:2:2, 16bpp, full scale (JPEG), deprecated in favor of PIX_FMT_YUV422P and setting color_range
    PIX_FMT_YUVJ444P,  ///< planar YUV 4:4:4, 24bpp, full scale (JPEG), deprecated in favor of PIX_FMT_YUV444P and setting color_range
    PIX_FMT_XVMC_MPEG2_MC,///< XVideo Motion Acceleration via common packet passing
    PIX_FMT_XVMC_MPEG2_IDCT,
    PIX_FMT_UYVY422,   ///< packed YUV 4:2:2, 16bpp, Cb Y0 Cr Y1
    PIX_FMT_UYYVYY411, ///< packed YUV 4:1:1, 12bpp, Cb Y0 Y1 Cr Y2 Y3
    PIX_FMT_BGR8,      ///< packed RGB 3:3:2,  8bpp, (msb)2B 3G 3R(lsb)
    PIX_FMT_BGR4,      ///< 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
    PIX_FMT_BGR4_BYTE, ///< packed RGB 1:2:1,  8bpp, (msb)1B 2G 1R(lsb)
    PIX_FMT_RGB8,      ///< packed RGB 3:3:2,  8bpp, (msb)2R 3G 3B(lsb)
    PIX_FMT_RGB4,      ///< 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
    PIX_FMT_RGB4_BYTE, ///< packed RGB 1:2:1,  8bpp, (msb)1R 2G 1B(lsb)
    PIX_FMT_NV12,      ///< 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)
    PIX_FMT_NV21,      ///< as above, but U and V bytes are swapped

    PIX_FMT_ARGB,      ///< packed ARGB 8:8:8:8, 32bpp, ARGBARGB...
    PIX_FMT_RGBA,      ///< packed RGBA 8:8:8:8, 32bpp, RGBARGBA...
    PIX_FMT_ABGR,      ///< packed ABGR 8:8:8:8, 32bpp, ABGRABGR...
    PIX_FMT_BGRA,      ///< packed BGRA 8:8:8:8, 32bpp, BGRABGRA...

    PIX_FMT_GRAY16BE,  ///<        Y        , 16bpp, big-endian
    PIX_FMT_GRAY16LE,  ///<        Y        , 16bpp, little-endian
    PIX_FMT_YUV440P,   ///< planar YUV 4:4:0 (1 Cr & Cb sample per 1x2 Y samples)
    PIX_FMT_YUVJ440P,  ///< planar YUV 4:4:0 full scale (JPEG), deprecated in favor of PIX_FMT_YUV440P and setting color_range
    PIX_FMT_YUVA420P,  ///< planar YUV 4:2:0, 20bpp, (1 Cr & Cb sample per 2x2 Y & A samples)
    PIX_FMT_VDPAU_H264,///< 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
    PIX_FMT_VDPAU_MPEG1,///< 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
    PIX_FMT_VDPAU_MPEG2,///< 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
    PIX_FMT_VDPAU_WMV3,///< 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
    PIX_FMT_VDPAU_VC1, ///< 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
    PIX_FMT_RGB48BE,   ///< packed RGB 16:16:16, 48bpp, 16R, 16G, 16B, the 2-byte value for each R/G/B component is stored as big-endian
    PIX_FMT_RGB48LE,   ///< packed RGB 16:16:16, 48bpp, 16R, 16G, 16B, the 2-byte value for each R/G/B component is stored as little-endian

    PIX_FMT_RGB565BE,  ///< packed RGB 5:6:5, 16bpp, (msb)   5R 6G 5B(lsb), big-endian
    PIX_FMT_RGB565LE,  ///< packed RGB 5:6:5, 16bpp, (msb)   5R 6G 5B(lsb), little-endian
    PIX_FMT_RGB555BE,  ///< packed RGB 5:5:5, 16bpp, (msb)1A 5R 5G 5B(lsb), big-endian, most significant bit to 0
    PIX_FMT_RGB555LE,  ///< packed RGB 5:5:5, 16bpp, (msb)1A 5R 5G 5B(lsb), little-endian, most significant bit to 0

    PIX_FMT_BGR565BE,  ///< packed BGR 5:6:5, 16bpp, (msb)   5B 6G 5R(lsb), big-endian
    PIX_FMT_BGR565LE,  ///< packed BGR 5:6:5, 16bpp, (msb)   5B 6G 5R(lsb), little-endian
    PIX_FMT_BGR555BE,  ///< packed BGR 5:5:5, 16bpp, (msb)1A 5B 5G 5R(lsb), big-endian, most significant bit to 1
    PIX_FMT_BGR555LE,  ///< packed BGR 5:5:5, 16bpp, (msb)1A 5B 5G 5R(lsb), little-endian, most significant bit to 1

    PIX_FMT_VAAPI_MOCO, ///< 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
    PIX_FMT_VAAPI_IDCT, ///< HW acceleration through VA API at IDCT entry-point, Picture.data[3] contains a vaapi_render_state struct which contains fields extracted from headers
    PIX_FMT_VAAPI_VLD,  ///< 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

    PIX_FMT_YUV420P16LE,  ///< planar YUV 4:2:0, 24bpp, (1 Cr & Cb sample per 2x2 Y samples), little-endian
    PIX_FMT_YUV420P16BE,  ///< planar YUV 4:2:0, 24bpp, (1 Cr & Cb sample per 2x2 Y samples), big-endian
    PIX_FMT_YUV422P16LE,  ///< planar YUV 4:2:2, 32bpp, (1 Cr & Cb sample per 2x1 Y samples), little-endian
    PIX_FMT_YUV422P16BE,  ///< planar YUV 4:2:2, 32bpp, (1 Cr & Cb sample per 2x1 Y samples), big-endian
    PIX_FMT_YUV444P16LE,  ///< planar YUV 4:4:4, 48bpp, (1 Cr & Cb sample per 1x1 Y samples), little-endian
    PIX_FMT_YUV444P16BE,  ///< planar YUV 4:4:4, 48bpp, (1 Cr & Cb sample per 1x1 Y samples), big-endian
    PIX_FMT_VDPAU_MPEG4,  ///< 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
    PIX_FMT_DXVA2_VLD,    ///< HW decoding through DXVA2, Picture.data[3] contains a LPDIRECT3DSURFACE9 pointer

    PIX_FMT_RGB444LE,  ///< packed RGB 4:4:4, 16bpp, (msb)4A 4R 4G 4B(lsb), little-endian, most significant bits to 0
    PIX_FMT_RGB444BE,  ///< packed RGB 4:4:4, 16bpp, (msb)4A 4R 4G 4B(lsb), big-endian, most significant bits to 0
    PIX_FMT_BGR444LE,  ///< packed BGR 4:4:4, 16bpp, (msb)4A 4B 4G 4R(lsb), little-endian, most significant bits to 1
    PIX_FMT_BGR444BE,  ///< packed BGR 4:4:4, 16bpp, (msb)4A 4B 4G 4R(lsb), big-endian, most significant bits to 1
    PIX_FMT_GRAY8A,    ///< 8bit gray, 8bit alpha
    PIX_FMT_BGR48BE,   ///< packed RGB 16:16:16, 48bpp, 16B, 16G, 16R, the 2-byte value for each R/G/B component is stored as big-endian
    PIX_FMT_BGR48LE,   ///< packed RGB 16:16:16, 48bpp, 16B, 16G, 16R, the 2-byte value for each R/G/B component is stored as little-endian

    //the following 10 formats have the disadvantage of needing 1 format for each bit depth, thus
    //If you want to support multiple bit depths, then using PIX_FMT_YUV420P16* with the bpp stored seperately
    //is better
    PIX_FMT_YUV420P9BE, ///< planar YUV 4:2:0, 13.5bpp, (1 Cr & Cb sample per 2x2 Y samples), big-endian
    PIX_FMT_YUV420P9LE, ///< planar YUV 4:2:0, 13.5bpp, (1 Cr & Cb sample per 2x2 Y samples), little-endian
    PIX_FMT_YUV420P10BE,///< planar YUV 4:2:0, 15bpp, (1 Cr & Cb sample per 2x2 Y samples), big-endian
    PIX_FMT_YUV420P10LE,///< planar YUV 4:2:0, 15bpp, (1 Cr & Cb sample per 2x2 Y samples), little-endian
    PIX_FMT_YUV422P10BE,///< planar YUV 4:2:2, 20bpp, (1 Cr & Cb sample per 2x1 Y samples), little-endian
    PIX_FMT_YUV422P10LE,///< planar YUV 4:2:2, 20bpp, (1 Cr & Cb sample per 2x1 Y samples), big-endian
    PIX_FMT_YUV444P9BE, ///< planar YUV 4:4:4, 27bpp, (1 Cr & Cb sample per 1x1 Y samples), little-endian
    PIX_FMT_YUV444P9LE, ///< planar YUV 4:4:4, 27bpp, (1 Cr & Cb sample per 1x1 Y samples), big-endian
    PIX_FMT_YUV444P10BE,///< planar YUV 4:4:4, 30bpp, (1 Cr & Cb sample per 1x1 Y samples), little-endian
    PIX_FMT_YUV444P10LE,///< planar YUV 4:4:4, 30bpp, (1 Cr & Cb sample per 1x1 Y samples), big-endian

    PIX_FMT_NB,        ///< number of pixel formats, DO NOT USE THIS if you want to link with shared libav* because the number of formats might differ between versions
};

#define PIX_FMT_Y400A PIX_FMT_GRAY8A

#if AV_HAVE_BIGENDIAN
#   define PIX_FMT_NE(be, le) PIX_FMT_##be
#else
#   define PIX_FMT_NE(be, le) PIX_FMT_##le
#endif

#define PIX_FMT_RGB32   PIX_FMT_NE(ARGB, BGRA)
#define PIX_FMT_RGB32_1 PIX_FMT_NE(RGBA, ABGR)
#define PIX_FMT_BGR32   PIX_FMT_NE(ABGR, RGBA)
#define PIX_FMT_BGR32_1 PIX_FMT_NE(BGRA, ARGB)

#define PIX_FMT_GRAY16 PIX_FMT_NE(GRAY16BE, GRAY16LE)
#define PIX_FMT_RGB48  PIX_FMT_NE(RGB48BE,  RGB48LE)
#define PIX_FMT_RGB565 PIX_FMT_NE(RGB565BE, RGB565LE)
#define PIX_FMT_RGB555 PIX_FMT_NE(RGB555BE, RGB555LE)
#define PIX_FMT_RGB444 PIX_FMT_NE(RGB444BE, RGB444LE)
#define PIX_FMT_BGR48  PIX_FMT_NE(BGR48BE,  BGR48LE)
#define PIX_FMT_BGR565 PIX_FMT_NE(BGR565BE, BGR565LE)
#define PIX_FMT_BGR555 PIX_FMT_NE(BGR555BE, BGR555LE)
#define PIX_FMT_BGR444 PIX_FMT_NE(BGR444BE, BGR444LE)

#define PIX_FMT_YUV420P9  PIX_FMT_NE(YUV420P9BE , YUV420P9LE)
#define PIX_FMT_YUV444P9  PIX_FMT_NE(YUV444P9BE , YUV444P9LE)
#define PIX_FMT_YUV420P10 PIX_FMT_NE(YUV420P10BE, YUV420P10LE)
#define PIX_FMT_YUV422P10 PIX_FMT_NE(YUV422P10BE, YUV422P10LE)
#define PIX_FMT_YUV444P10 PIX_FMT_NE(YUV444P10BE, YUV444P10LE)
#define PIX_FMT_YUV420P16 PIX_FMT_NE(YUV420P16BE, YUV420P16LE)
#define PIX_FMT_YUV422P16 PIX_FMT_NE(YUV422P16BE, YUV422P16LE)
#define PIX_FMT_YUV444P16 PIX_FMT_NE(YUV444P16BE, YUV444P16LE)

#endif /* AVUTIL_PIXFMT_H */ 

灰度与YUV的关系非常简单 - YUV的"Y"与灰度完全相同.

将灰度转换为YUV的简单方法是

有关比例之间的转换,请参阅此参考:

相应地:

Y  =      (0.257 * R) + (0.504 * G) + (0.098 * B) + 16
Cr = V =  (0.439 * R) - (0.368 * G) - (0.071 * B) + 128
Cb = U = -(0.148 * R) - (0.291 * G) + (0.439 * B) + 128

Now: 
For a Grayscale image (W): 

R = W;
G = W;
B = W;

Keeping this: 

Y[i] = 0.895 * W[i] + 16. 
U[i] = 128 (fixed value)
V[i] = 128 (fxied value)

你实际上可以使用几乎相同的Y [i] = W [i].128值表示在0-256的缩放/移位基数中的'0',其签名为无符号转换.

因此,您需要保留的是将此其他内存区域Y和U创建为固定值,并将此帧提供给ffmpeg.

我不确定,但通过恰当地告诉FFMPEG,它只在内部完成.您提供的RGB值也同样适用于那里; 这也不是MPEG的原生.

因此,请查看FFMPEG的API,它可以让您这样做.

奖励
请记住,在过去的好日子里,有黑白(灰度)电视机.新的彩色电视机需要兼容旧的彩色电视机,因此颜色信息以U和V的形式添加(有时也称为YCbCr - 其中Cb和Cr称为色度,分别是UV的线性变化)这个背景).