I have a video that I'm processing and transcoding to another format via ffmpeg. I've come across this before where the reported fps in ffprobe seems to be half of what it is when played but don't understand why. Problem is that when ffmpeg processes this file, the output is using the seemingly misreported framerate and I have to override it and redo the file.
Here's the stream info for the video stream:
$ ffprobe -i file.mp4 -print_format json -show_streams 2>/dev/null
{
"index": 0,
"codec_name": "h264",
"codec_long_name": "H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10",
"profile": "Main",
"codec_type": "video",
"codec_tag_string": "[0][0][0][0]",
"codec_tag": "0x0000",
"width": 1920,
"height": 1080,
"coded_width": 1920,
"coded_height": 1080,
"closed_captions": 0,
"has_b_frames": 1,
"sample_aspect_ratio": "1:1",
"display_aspect_ratio": "16:9",
"pix_fmt": "yuv420p",
"level": 40,
"chroma_location": "left",
"field_order": "progressive",
"refs": 1,
"is_avc": "true",
"nal_length_size": "4",
"r_frame_rate": "15/1",
"avg_frame_rate": "15/1",
"time_base": "1/1000",
"start_pts": 67,
"start_time": "0.067000",
"bits_per_raw_sample": "8",
"disposition": {
"default": 1,
"dub": 0,
"original": 0,
"comment": 0,
"lyrics": 0,
"karaoke": 0,
"forced": 0,
"hearing_impaired": 0,
"visual_impaired": 0,
"clean_effects": 0,
"attached_pic": 0,
"timed_thumbnails": 0
}
},
How can I tell this is the case and not actually 15fps? Looking for a programmatic way to detect this case.
$ ffprobe -version
ffprobe version 4.4.1-full_build-www.gyan.dev Copyright (c) 2007-2021 the FFmpeg developers
built with gcc 11.2.0 (Rev1, Built by MSYS2 project)
configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-lzma --enable-libsnappy --enable-zlib --enable-librist --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libdav1d --enable-libzvbi --enable-librav1e --enable-libsvtav1 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libaom --enable-libopenjpeg --enable-libvpx --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-d3d11va --enable-dxva2 --enable-libmfx --enable-libglslang --enable-vulkan --enable-opencl --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
libavutil 56. 70.100 / 56. 70.100
libavcodec 58.134.100 / 58.134.100
libavformat 58. 76.100 / 58. 76.100
libavdevice 58. 13.100 / 58. 13.100
libavfilter 7.110.100 / 7.110.100
libswscale 5. 9.100 / 5. 9.100
libswresample 3. 9.100 / 3. 9.100
libpostproc 55. 9.100 / 55. 9.100
Windows build
FFprobewithshow_packetsargument:ffprobe -select_streams v -show_packets file.mp4. Look atpts_timeandduration_time. For 15 fps the minimum delta between two pts should be0.0667seconds, and the duration should be0.0667seconds. You may look for frames counting, and divide the number of frames by video duration.