尽管我只向文件添加了旋转元数据，但我的输入文件和输出文件的持续时间却不同。为什么 ffmpeg 会为文件创建不同的持续时间？
输入文件的 ffprobe 输出：
{
"streams": [
{
"index": 0,
"codec_name": "h264",
"codec_long_name": "H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10",
"profile": "High",
"codec_type": "video",
"codec_time_base": "1/60",
"codec_tag_string": "[27][0][0][0]",
"codec_tag": "0x001b",
"width": 1920,
"height": 1088,
"coded_width": 1920,
"coded_height": 1088,
"has_b_frames": 1,
"sample_aspect_ratio": "1:1",
"display_aspect_ratio": "30:17",
"pix_fmt": "yuv420p",
"level": 41,
"chroma_location": "left",
"field_order": "progressive",
"refs": 1,
"is_avc": "false",
"nal_length_size": "0",
"id": "0x102",
"r_frame_rate": "30/1",
"avg_frame_rate": "30/1",
"time_base": "1/90000",
"start_pts": 10356033,
"start_time": "115.067033",
"duration_ts": 540171000,
"duration": "6001.900000",
"bits_per_raw_sample": "8",
"disposition": {
"default": 0,
"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
}
},
}
然后我运行 ffmpeg 命令
.\ffmpeg.exe -i "in.mp4" -map_metadata 0 -metadata:s:v rotate="90" -codec copy "out.mp4"
它会生成一个包含以下 ffprobe 输出的文件
{
"streams": [
{
"index": 0,
"codec_name": "h264",
"codec_long_name": "H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10",
"profile": "High",
"codec_type": "video",
"codec_time_base": "31769997/1906136018",
"codec_tag_string": "avc1",
"codec_tag": "0x31637661",
"width": 1920,
"height": 1088,
"coded_width": 1920,
"coded_height": 1088,
"has_b_frames": 1,
"sample_aspect_ratio": "1:1",
"display_aspect_ratio": "30:17",
"pix_fmt": "yuv420p",
"level": 41,
"chroma_location": "left",
"refs": 1,
"is_avc": "true",
"nal_length_size": "4",
"r_frame_rate": "30/1",
"avg_frame_rate": "953068009/31769997",
"time_base": "1/90000",
"start_pts": 42480,
"start_time": "0.472000",
"duration_ts": 1045760490,
"duration": "11619.561000",
"bit_rate": "4376790",
"bits_per_raw_sample": "8",
"nb_frames": "348561",
"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
},
"tags": {
"rotate": "270",
"language": "und",
"handler_name": "VideoHandler"
},
"side_data_list": [
{
"side_data_type": "Display Matrix",
"displaymatrix": "\n00000000: 0 -65536 0\n00000001: 65536 0 0\n00000002: 0 0 1073741824\n",
"rotation": 90
}
]
},
}