1、查看视频流index的方法：
方法一、ffprobe /Users/laa/Desktop/abc/视频.mp4
ffprobe -select_streams 0 -show_packets /Users/laa/Desktop/abc/shipin.mp4 |grep flags=
方法二、通过-show_streams参数可以查看到多媒体文件中的流信息，流的信息使用STREAMS标签括起来，可以看到
index=0codec_name=h264
输入命令：ffprobe -show_streams /Users/lily/Desktop/白雾/只有一个关键帧.mp4 输出如下：ffprobe version 3.4.2 Copyright (c) 2007-2018 the FFmpeg developers built with Apple LLVM version 9.0.0 (clang-900.0.39.2) configuration: --prefix=/usr/local/Cellar/ffmpeg/3.4.2 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --disable-jack --enable-gpl --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma libavutil 55. 78.100 / 55. 78.100 libavcodec 57.107.100 / 57.107.100 libavformat 57. 83.100 / 57. 83.100 libavdevice 57. 10.100 / 57. 10.100 libavfilter 6.107.100 / 6.107.100 libavresample 3. 7. 0 / 3. 7. 0 libswscale 4. 8.100 / 4. 8.100 libswresample 2. 9.100 / 2. 9.100 libpostproc 54. 7.100 / 54. 7.100Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/Users/liaa/Desktop/abc/只有一个关键帧.mp4': Metadata: major_brand : isom minor_version : 512 compatible_brands: isomiso2avc1mp41 encoder : Lavf57.25.100 comment : GIFSHOW [26196011][iOS][10.3.3][iPhone7,1][5.2.0.222][Camera:b] Duration: 00:00:11.54, start: 0.000000, bitrate: 927 kb/s Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 720x960, 858 kb/s, 19.49 fps, 20 tbr, 19200 tbn, 1200 tbc (default) Metadata: handler_name : VideoHandler Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 63 kb/s (default) Metadata: handler_name : SoundHandler[STREAM]index=0codec_name=h264codec_long_name=H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10profile=Highcodec_type=videocodec_time_base=197/7680codec_tag_string=avc1codec_tag=0x31637661width=720height=960coded_width=720coded_height=960has_b_frames=2sample_aspect_ratio=0:1display_aspect_ratio=0:1pix_fmt=yuv420plevel=52color_range=unknowncolor_space=unknowncolor_transfer=unknowncolor_primaries=unknownchroma_location=leftfield_order=unknowntimecode=N/Arefs=1is_avc=truenal_length_size=4id=N/Ar_frame_rate=20/1avg_frame_rate=3840/197time_base=1/19200start_pts=0start_time=0.000000duration_ts=221626duration=11.543021bit_rate=858673max_bit_rate=N/Abits_per_raw_sample=8nb_frames=225nb_read_frames=N/Anb_read_packets=N/ADISPOSITION:default=1DISPOSITION:dub=0DISPOSITION:original=0DISPOSITION:comment=0DISPOSITION:lyrics=0DISPOSITION:karaoke=0DISPOSITION:forced=0DISPOSITION:hearing_impaired=0DISPOSITION:visual_impaired=0DISPOSITION:clean_effects=0DISPOSITION:attached_pic=0DISPOSITION:timed_thumbnails=0TAG:language=undTAG:handler_name=VideoHandler[/STREAM][STREAM]index=1codec_name=aaccodec_long_name=AAC (Advanced Audio Coding)profile=LCcodec_type=audiocodec_time_base=1/44100codec_tag_string=mp4acodec_tag=0x6134706dsample_fmt=fltpsample_rate=44100channels=1channel_layout=monobits_per_sample=0id=N/Ar_frame_rate=0/0avg_frame_rate=0/0time_base=1/44100start_pts=0start_time=0.000000duration_ts=503931duration=11.427007bit_rate=63471max_bit_rate=63471bits_per_raw_sample=N/Anb_frames=493nb_read_frames=N/Anb_read_packets=N/ADISPOSITION:default=1DISPOSITION:dub=0DISPOSITION:original=0DISPOSITION:comment=0DISPOSITION:lyrics=0DISPOSITION:karaoke=0DISPOSITION:forced=0DISPOSITION:hearing_impaired=0DISPOSITION:visual_impaired=0DISPOSITION:clean_effects=0DISPOSITION:attached_pic=0DISPOSITION:timed_thumbnails=0TAG:language=undTAG:handler_name=SoundHandler[/STREAM]
2.使用
ffprobe -select_streams 0 -show_packets，查看关键帧数量，最后一行的就是： 其中，
-select_streams 后面跟视频的index，上个命令可以看到。
ffprobe -select_streams 0 -show_packets /Users/laa/Desktop/abc/只有一个关键帧.mp4 |grep flags=K |wc -lffprobe version 3.4.2 Copyright (c) 2007-2018 the FFmpeg developers built with Apple LLVM version 9.0.0 (clang-900.0.39.2) configuration: --prefix=/usr/local/Cellar/ffmpeg/3.4.2 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --disable-jack --enable-gpl --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma libavutil 55. 78.100 / 55. 78.100 libavcodec 57.107.100 / 57.107.100 libavformat 57. 83.100 / 57. 83.100 libavdevice 57. 10.100 / 57. 10.100 libavfilter 6.107.100 / 6.107.100 libavresample 3. 7. 0 / 3. 7. 0 libswscale 4. 8.100 / 4. 8.100 libswresample 2. 9.100 / 2. 9.100 libpostproc 54. 7.100 / 54. 7.100Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/Users/laa/Desktop/abc/只有一个关键帧.mp4': Metadata: major_brand : isom minor_version : 512 compatible_brands: isomiso2avc1mp41 encoder : Lavf57.25.100 comment : GIFSHOW [26196011][iOS][10.3.3][iPhone7,1][5.2.0.222][Camera:b] Duration: 00:00:11.54, start: 0.000000, bitrate: 927 kb/s Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 720x960, 858 kb/s, 19.49 fps, 20 tbr, 19200 tbn, 1200 tbc (default) Metadata: handler_name : VideoHandler Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 63 kb/s (default) Metadata: handler_name : SoundHandler 1