查看“︁FFmpeg”︁的源代码

===移除或寫入後設資料===
{|
|-
| colspan="4" | {{stpnk|remove all metadata}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-map_metadata -1 -map_chapters -1 -metadata:s handler_name= -metadata:s vendor_id= -disposition 0</syntaxhighlight>
|-
| colspan="4" style="padding-bottom: 0.5rem; padding-top: 0.5rem;" | 或透過組合選用以下來按需添加。'''須知'''：不是所有的檔案類型／容器都支援以下所有的關鍵字。
|-
| style="padding-right: 0.8rem;" | {{stsgn|album}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata album=""</syntaxhighlight>
| style="padding-right: 0.8rem;" | {{stsgn|album artist}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata album_artist=""</syntaxhighlight>
| style="padding-right: 0.8rem;" | {{stsgn|artist}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata artist=""</syntaxhighlight>
| {{stsgn|author}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata author=""</syntaxhighlight>
|-
| style="padding-right: 0.8rem;" | {{stsgn|comment}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata comment=""</syntaxhighlight>
| style="padding-right: 0.8rem;" | {{stsgn|compilation}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata compilation=""</syntaxhighlight>
| style="padding-right: 0.8rem;" | {{stsgn|composer}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata composer=""</syntaxhighlight>
| {{stsgn|date}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata date=""</syntaxhighlight>
|-
| style="padding-right: 0.8rem;" | {{stsgn|disc (no/total)}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata disc=""</syntaxhighlight>
| style="padding-right: 0.8rem;" | {{stsgn|episode ID}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata episode_id=""</syntaxhighlight>
| style="padding-right: 0.8rem;" | {{stsgn|episode sort}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata episode_sort=""</syntaxhighlight>
| {{stsgn|genre}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata genre=""</syntaxhighlight>
|-
| style="padding-right: 0.8rem;" | {{stsgn|grouping}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata grouping=""</syntaxhighlight>
| style="padding-right: 0.8rem;" | {{stsgn|language}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata language=""</syntaxhighlight>
| style="padding-right: 0.8rem;" | {{stsgn|location}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata location=""</syntaxhighlight>
| {{stsgn|lyrics}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata lyrics=""</syntaxhighlight>
|-
| style="padding-right: 0.8rem;" | {{stsgn|make}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata make=""</syntaxhighlight>
| style="padding-right: 0.8rem;" | {{stsgn|model}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata model=""</syntaxhighlight>
| style="padding-right: 0.8rem;" | {{stsgn|network}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata network=""</syntaxhighlight>
| {{stsgn|performer}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata performer=""</syntaxhighlight>
|-
| style="padding-right: 0.8rem;" | {{stsgn|publisher}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata publisher=""</syntaxhighlight>
| style="padding-right: 0.8rem;" | {{stsgn|season number}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata season_number=""</syntaxhighlight>
| style="padding-right: 0.8rem;" | {{stsgn|show}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata show=""</syntaxhighlight>
| {{stsgn|synopsis}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata synopsis=""</syntaxhighlight>
|-
| style="padding-right: 0.8rem;" | {{stsgn|title}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata title=""</syntaxhighlight>
| style="padding-right: 0.8rem;" | {{stsgn|track (no/total)}}<syntaxhighlight lang="text" copy style="margin-bottom: 0;">-metadata track=""</syntaxhighlight>
| 
| 
|}
===downscaling===
使用
<syntaxhighlight lang="text" copy>
-vf format=gbrpf32le,zscale=transferin=bt709:transfer=linear,zscale=w='if(gte(iw,ih),min(1280,iw),-2)':h='if(lt(iw,ih),min(1280,ih),-2)':f=lanczos:param_a=4:param_b=0.6:dither=error_diffusion,zscale=transferin=linear:transfer=bt709,unsharp=5:5:0.5:3:3:0.0,format=yuv444p10le,setsar=1
</syntaxhighlight>
來 down&#173;sc&#173;a&#173;le, 此處以 down&#173;sc&#173;a&#173;le 到使其長邊不超過 12<wbr />80 px 為例。

其中，<code>di<wbr />ther<wbr />=<wbr />er<wbr />ror<wbr />_<wbr />dif<wbr />fu<wbr />sion</code> 部分可以改為 <code>di<wbr />ther<wbr />=<wbr />no<wbr />ne</code> 來不添加任何 di&#173;the&#173;ring, 或刪去以讓 {{spmono|ff<wbr />mpeg}} 採用預設。

加入 <code>hq<wbr />dn<wbr />3d<wbr />=<wbr />1<wbr />:<wbr />1<wbr />:<wbr />2<wbr />:<wbr />2,</code> 直接在 <code>-<wbr />vf </code>&#160;後面可略微「抹勻」(de&#173;no&#173;i&#173;sing) 畫面。更強烈的「抹勻」效果可以透過調整 {{spmono|hq<wbr />dn<wbr />3d}} 的值來實現，比如改用 <code>hq<wbr />dn<wbr />3d<wbr />=<wbr />1<wbr />.<wbr />5<wbr />:<wbr />1<wbr />.<wbr />0<wbr />:<wbr />3<wbr />:<wbr />2,</code> 或 <code>hq<wbr />dn<wbr />3d<wbr />=<wbr />2<wbr />:<wbr />1<wbr />:<wbr />2<wbr />:<wbr />1,</code>.

便利貼：
{{stsgn|no dithering}}<syntaxhighlight lang="text" copy>-vf format=gbrpf32le,zscale=transferin=bt709:transfer=linear,zscale=w='if(gte(iw,ih),min(1280,iw),-2)':h='if(lt(iw,ih),min(1280,ih),-2)':f=lanczos:param_a=4:param_b=0.6:dither=none,zscale=transferin=linear:transfer=bt709,unsharp=5:5:0.5:3:3:0.0,format=yuv444p10le,setsar=1</syntaxhighlight>
{{stsgn|no dithering, no sharpening}}<syntaxhighlight lang="text" copy>-vf format=gbrpf32le,zscale=transferin=bt709:transfer=linear,zscale=w='if(gte(iw,ih),min(1280,iw),-2)':h='if(lt(iw,ih),min(1280,ih),-2)':f=lanczos:param_a=4:param_b=0.6:dither=none,zscale=transferin=linear:transfer=bt709,format=yuv444p10le,setsar=1</syntaxhighlight>
{{stsgn|having both diffusion and hqdn3d}}<syntaxhighlight lang="text" copy>-vf hqdn3d=1:1:2:2,format=gbrpf32le,zscale=transferin=bt709:transfer=linear,zscale=w='if(gte(iw,ih),min(1280,iw),-2)':h='if(lt(iw,ih),min(1280,ih),-2)':f=lanczos:param_a=4:param_b=0.6:dither=error_diffusion,zscale=transferin=linear:transfer=bt709,unsharp=5:5:0.5:3:3:0.0,format=yuv444p10le,setsar=1</syntaxhighlight>
{{stsgn|no dithering, but with hqdn3d}}<syntaxhighlight lang="text" copy>-vf hqdn3d=1:1:2:2,format=gbrpf32le,zscale=transferin=bt709:transfer=linear,zscale=w='if(gte(iw,ih),min(1280,iw),-2)':h='if(lt(iw,ih),min(1280,ih),-2)':f=lanczos:param_a=4:param_b=0.6:dither=none,zscale=transferin=linear:transfer=bt709,unsharp=5:5:0.5:3:3:0.0,format=yuv444p10le,setsar=1</syntaxhighlight>
若 sc&#173;a&#173;ling 的原則是依照短邊不超過 7<wbr />20 px 為準，則可將以上命令塊中的 <code>z<wbr />sca<wbr />le<wbr />=<wbr />w<wbr />=<wbr />'if<wbr />(<wbr />gte<wbr />(<wbr />iw,<wbr />ih),<wbr />min<wbr />(<wbr />12<wbr />80,<wbr />iw),<wbr />-<wbr />2)'<wbr />:<wbr />h<wbr />=<wbr />'if<wbr />(<wbr />lt<wbr />(<wbr />iw,<wbr />ih),<wbr />min<wbr />(<wbr />12<wbr />80,<wbr />ih),<wbr />-<wbr />2)'</code> 部分以 <code>z<wbr />sca<wbr />le<wbr />=<wbr />w<wbr />=<wbr />'if<wbr />(<wbr />lt<wbr />(<wbr />iw,<wbr />ih),<wbr />min<wbr />(<wbr />7<wbr />20,<wbr />iw),<wbr />-<wbr />2)'<wbr />:<wbr />h<wbr />=<wbr />'if<wbr />(<wbr />gte<wbr />(<wbr />iw,<wbr />ih),<wbr />min<wbr />(<wbr />7<wbr />20,<wbr />ih),<wbr />-<wbr />2)'</code> 取代之。

===使用封面圖片與歌曲來制作歌曲的視訊檔===
參考以下兩個模板{{cmd}}
{{stsgn|1080p crf 25 + 256k<small>VBR</small>}}<syntaxhighlight lang="text" copy>ffmpeg -loop 1 -i cover.png -i song.wav -vf format=rgba64le,colorchannelmixer=aa=1,crop='floor(min(iw,ih)/2)*2:floor(min(iw,ih)/2)*2',scale=-2:1080:flags=lanczos+accurate_rnd+full_chroma_inp+full_chroma_int:param0=4,format=yuv444p10le,setsar=1 -r 1 -c:v libsvtav1 -pix_fmt yuv420p10le -preset 1 -crf 25 -g 720 -svtav1-params "tune=0:enable-qm=1:aq-mode=1:lookahead=120:scd=1" -c:a libopus -b:a 256k -t hh:mm:ss.xx -map_metadata -1 -map_chapters -1 -metadata:s handler_name= -metadata:s vendor_id= -disposition 0 -metadata album="" -metadata album_artist="" -metadata artist="" -metadata composer="" -metadata date="" -metadata genre="" -metadata title="" "output.webm"</syntaxhighlight>
{{stsgn|720p crf 23 + 160k<small>VBR</small>}}<syntaxhighlight lang="text" copy>ffmpeg -loop 1 -i cover.png -i song.flac -vf format=rgba64le,colorchannelmixer=aa=1,crop='floor(min(iw,ih)/2)*2:floor(min(iw,ih)/2)*2',scale=-2:720:flags=lanczos+accurate_rnd+full_chroma_inp+full_chroma_int:param0=4,format=yuv444p10le,setsar=1 -r 1 -c:v libsvtav1 -pix_fmt yuv420p10le -preset 1 -crf 23 -g 720 -svtav1-params "tune=0:enable-qm=1:aq-mode=1:lookahead=120:scd=1" -c:a libopus -b:a 160k -t hh:mm:ss.xx -map_metadata -1 -map_chapters -1 -metadata:s handler_name= -metadata:s vendor_id= -disposition 0 -metadata album="" -metadata album_artist="" -metadata artist="" -metadata composer="" -metadata date="" -metadata genre="" -metadata title="" "output-small.webm"</syntaxhighlight>
不要嘗試使用 <code>-short<wbr />est</code> 來取代 <code>-t hh<wbr />:<wbr />mm<wbr />:<wbr />ss<wbr />.<wbr />xx</code> (具體時間須視歌曲時長手動填入), 因為這樣得出的長度一定是長於歌曲的具體時長的。

==={{spmono|lib<wbr />svt<wbr />av1}}===
'''AV<wbr />1 在任何情況下都應當僅作為網路分發考慮，如果以在地蒐藏為目的，仍需認準 H<wbr />265.''' 一個 {{spmono|crf}} 在 20 到 23 之間的 {{spmono|very<wbr />slow}} 的 H<wbr />265 至今仍可在任何方面（除了速度）遠超 AV<wbr />1.

在前述的前提下，AV<wbr />1 在低位元速率的應用場合中，表現還是要遠好於 H<wbr />264 的，因此比較適合在網路上使用。

總體上來說，可以套用以下設定{{cmd}}
<syntaxhighlight lang="text" copy>-c:v libsvtav1 -pix_fmt yuv420p10le -preset 2 -crf 33 -svtav1-params "tune=0:enable-qm=1:aq-mode=1:lookahead=120:scd=1"</syntaxhighlight>
來壓出一個看起來還說得過去的質量。{{spmono|crf}} 設在 33 上看起來不高，但是其實調高（其實是調低）它的設定也未見得能將畫質提高到哪裡去，反而會徒增檔案的大小，得不償失。{{spmono|lib<wbr />svt<wbr />av1}} 的優勢在於速度快，而且在低位元速率下效果好，因此維持 {{spmono|crf}} 設在 33 上其實並不太過「低劣」，如果畫面內容動得厲害，還可以降至 36, 39, 42, 乃至 45{{cmd}}到 45 就確實有點渣了，但也不是不能看。如果畫面著實平穩，少有動的，則減到 30 或者 27 就了得了，再減並無任何必要，要時刻銘記，AV<wbr />1 只適合在網路上分發，因此低位元速率下一個看得過去的畫質才是 AV<wbr />1 的長處。
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