我想要像原始源一样导出每一帧，在 webm 视频中是 alpha/透明视频轨道，如果我尝试使用我的基本命令导出，则会以黑色背景导出。
ffmpeg \
-hide_banner \
-loglevel error\
-stats \
-i ${DIRECTORY_CONVERT_VIDEO_TO_FRAMES}${videofile} \
-vf "scale=${new_width}:${new_height}" \
"${DIRECTORY_CONVERTED_FRAMES}"%04d.png
我添加了-c:v png，-q:v 0但format=rgba效果仍然相同。
ffmpeg \
-hide_banner \
-loglevel error \
-stats \
-i video/ok.webm \
-vf "scale=${new_width}:${new_height},format=rgba" \
-c:v png \
-q:v 0 \
"${DIRECTORY_CONVERTED_FRAMES}"%04d.png
请帮帮我。我忘了，视频元数据：
ffprobe -show\_streams video/ok.webm
ffprobe version n6.1.1 Copyright (c) 2007-2023 the FFmpeg developers
built with gcc 13.2.1 (GCC) 20230801
configuration: --prefix=/usr --disable-debug --disable-static --disable-strippi
ng --enable-amf --enable-avisynth --enable-cuda-llvm --enable-lto --enable-fontconfig --enable-frei0r --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libdav1d --enable-libdrm --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libharfbuzz --enable-libiec61883 --enable-libjack --enable-libjxl --enable-libmodplug --enable-libmp3lame --enable-libopencore\_amrnb --enable-libopencore\_amrwb --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libplacebo --enable-libpulse --enable-librav1e --enable-librsvg --enable-librubberband --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpl --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid --enable-libzimg --enable-nvdec --enable-nvenc --enable-opencl --enable-opengl --enable-shared --enable-vapoursynth --enable-version3 --enable-vulkan libavutil 58. 29.100 / 58. 29.100
libavcodec 60. 31.102 / 60. 31.102
libavformat 60. 16.100 / 60. 16.100
libavdevice 60. 3.100 / 60. 3.100
libavfilter 9. 12.100 / 9. 12.100
libswscale 7. 5.100 / 7. 5.100
libswresample 4. 12.100 / 4. 12.100
libpostproc 57. 3.100 / 57. 3.100
Input #0, matroska,webm, from 'video/ok.webm':
Metadata:
ENCODER : Lavf60.16.100
Duration: 00:00:05.00, start: 0.000000, bitrate: 2580 kb/s
Stream #0:0: Video: vp9 (Profile 0), yuv420p(tv, progressive), 600x1040, SAR 1:
1 DAR 15:26, 30 fps, 30 tbr, 1k tbn Metadata:
alpha\_mode : 1
ENCODER : Lavc60.31.102 libvpx-vp9
DURATION : 00:00:05.000000000
\[STREAM\]
index=0
codec\_name=vp9
codec\_long\_name=Google VP9
profile=Profile 0
codec\_type=video
codec\_tag\_string=\[0\]\[0\]\[0\]\[0\]
codec\_tag=0x0000
width=600
height=1040
coded\_width=600
coded\_height=1040
closed\_captions=0
film\_grain=0
has\_b\_frames=0
sample\_aspect\_ratio=1:1
display\_aspect\_ratio=15:26
pix\_fmt=yuv420p
level=-99
color\_range=tv
color\_space=unknown
color\_transfer=unknown
color\_primaries=unknown
chroma\_location=unspecified
field\_order=progressive
refs=1
id=N/A
r\_frame\_rate=30/1
avg\_frame\_rate=30/1
time\_base=1/1000
start\_pts=0
start\_time=0.000000
duration\_ts=N/A
duration=N/A
bit\_rate=N/A
max\_bit\_rate=N/A
bits\_per\_raw\_sample=N/A
nb\_frames=N/A
nb\_read\_frames=N/A
nb\_read\_packets=N/A
DISPOSITION:default=0
DISPOSITION:dub=0
DISPOSITION:original=0
DISPOSITION:comment=0
DISPOSITION:lyrics=0
DISPOSITION:karaoke=0
DISPOSITION:forced=0
DISPOSITION:hearing\_impaired=0
DISPOSITION:visual\_impaired=0
DISPOSITION:clean\_effects=0
DISPOSITION:attached\_pic=0
DISPOSITION:timed\_thumbnails=0
DISPOSITION:non\_diegetic=0
DISPOSITION:captions=0
DISPOSITION:descriptions=0
DISPOSITION:metadata=0
DISPOSITION:dependent=0
DISPOSITION:still\_image=0
TAG:alpha\_mode=1
TAG:ENCODER=Lavc60.31.102 libvpx-vp9
TAG:DURATION=00:00:05.000000000
\[/STREAM\]
答案1
要解码 alpha，您需要强制使用 vpx 解码器。
对于 VP9，设置ffmpeg -c:v libvpx-vp9 -i video/ok.webm ...