{"id":5118,"date":"2025-05-08T18:55:00","date_gmt":"2025-05-08T09:55:00","guid":{"rendered":"https:\/\/zeoninc.com\/blog\/?p=5118"},"modified":"2025-05-08T15:15:24","modified_gmt":"2025-05-08T06:15:24","slug":"may2-2","status":"publish","type":"post","link":"https:\/\/zeoninc.com\/blog\/2025\/05\/08\/may2-2\/","title":{"rendered":"javascript\u3067MP4\u30bf\u30b0\u306e\u30d1\u30fc\u30b9"},"content":{"rendered":"\n

\u958b\u767a\u30b9\u30bf\u30c3\u30d5AH\u3067\u3059\u3002<\/p>\n\n\n\n

\u5148\u65e5Chrome\u306b\u3066Mediarecorder\u3092\u30b3\u30fc\u30c7\u30c3\u30afMP4\u6307\u5b9a\u3067\u884c\u3063\u305f\u3068\u3053\u308d\u3001\u6307\u5b9a\u3057\u305f\u6570\u5024\u3068\u7570\u306a\u3063\u305f\u79d2\u6570\u3067\u30e1\u30c7\u30a3\u30a2\u3092\u5207\u308a\u51fa\u3057\u3066\u304d\u305f\u4e8b\u4ef6\u304c\u3042\u308a\u307e\u3057\u305f\u3002
\u7279\u306b\u30a8\u30e9\u30fc\u3082\u7121\u3057\u3060\u3063\u305f\u306e\u3067\u3053\u308c\u304c\u4ed5\u69d8\u3068\u306a\u308b\u3068\u4eca\u5f8c\u304d\u3063\u3061\u308a\u6307\u5b9a\u3057\u305f\u79d2\u6570\u3067\u5207\u308a\u51fa\u3057\u3066\u304d\u3066\u304f\u308c\u308bchrome\u3068\u305d\u3046\u3067\u306a\u3044chrome\u3092\u5206\u3051\u308b\u5fc5\u8981\u304c\u3042\u308b\u304b\u3082\uff1f
\u3068\u3044\u3046\u3053\u3068\u3067\u51fa\u529b\u3055\u308c\u305fMP4\u306e\u79d2\u6570\u3092\u78ba\u8a8d\u3059\u308b\u5fc5\u8981\u304c\u3042\u308b\u305f\u3081\u3061\u3087\u3063\u3068MP4\u306e\u30d1\u30fc\u30b9\u3092\u66f8\u3044\u3066\u307f\u3088\u3046\u3068\u601d\u3044\u307e\u3059\u3002
\u672c\u6765\u306a\u3089MP4\u5185\u306etimescale\u3084duration\u3067\u5224\u5b9a\u3059\u308b\u306e\u3067\u3059\u304c\u30e9\u30a4\u30d6\u30bd\u30fc\u30b9\u306a\u306e\u3067\u307e\u3063\u305f\u304f\u308f\u304b\u3089\u306a\u3044\u72b6\u614b\u3068\u306a\u3063\u3066\u304a\u308a\u307e\u3059\u3002
\u8a73\u3057\u304f\u79d2\u6570\u3092\u77e5\u308a\u305f\u3044\u65b9\u306fMP4\u306e\u4ed5\u69d8\u3092\u30c1\u30a7\u30c3\u30af\u3057\u3066\u304f\u3060\u3055\u3044\u3002
\u3053\u3053\u3067\u306f\u3042\u304f\u307e\u3067\u30bf\u30b0\u3060\u3051\u62bd\u51fa\u3057\u307e\u3059\u3002<\/p>\n\n\n\n

\u30bd\u30fc\u30b9\u3067\u3059\u3002<\/p>\n\n\n\n

fetch(‘.\/test.mp4’)
.then(function(response){<\/p>\n\n\n\n

return response.arrayBuffer();<\/code><\/pre>\n\n\n\n
})
.then(function(buffer){<\/p>\n\n\n\n
const decoder = new TextDecoder('utf-8');\n\nconst mp4data = new Uint8Array(buffer);\n\nlet pos = 0;\n\nlet tag_size = 0;\n\nlet depth = 0;\n\nlet depth_array = [];\n\nwhile(pos <= mp4data.length){\n\n    const tag = decoder.decode(mp4data.slice(pos+4,pos+8));\n\n    if(\/[a-z]{4}\/.test(tag)){\n\n        let depth_str = '';\n\n        for(let i = depth; i > 0; i--){\n\n            depth_str += '-';\n\n        }\n        console.log(depth_str+tag);\n\n\n        tag_size = new DataView(mp4data.slice(pos,pos+4).buffer).getUint32(0,false);\n\n        depth_array.push(tag_size+pos);\n\n        pos += 8;\n        depth++;\n\n\n    }else{\n\n        pos += tag_size - 8;\n\n        for(let j = depth_array.length; j >= 0; j--){\n\n            if(depth_array[j]){\n\n                if(pos >= depth_array[j]){\n\n                    depth = j;\n\n                    depth_array.pop();\n\n                }\n\n            }\n\n        }\n\n    }\n\n} <\/code><\/pre>\n\n\n\n
});<\/p>\n\n\n\n
node.js\u3067\u5143\u306e\u30bd\u30fc\u30b9\u3092\u4f5c\u308a\u307e\u3057\u305f\u3002
\u30bf\u30b0\u540d\u3084\u30bf\u30b0\u306e\u30b5\u30a4\u30ba\u3092\u53d6\u308a\u3084\u3059\u3044\u306e\u3067\u3059\u304cjavascript\u306e\u5834\u5408\u82e5\u5e72\u624b\u9806\u304c\u9055\u3046\u3063\u307d\u3044\u306e\u3067chatgpt\u306b\u805e\u3044\u3066\u5909\u66f4\u3057\u307e\u3057\u305f\u3002<\/p>\n\n\n\n
const decoder = new TextDecoder(‘utf-8’);
const tag = decoder.decode(mp4data.slice(pos+4,pos+8));<\/p>\n\n\n\n
TextDecorder\u3067decode\u3059\u308c\u3070\u826f\u3044\u3089\u3057\u3044\u3067\u3059\u3002\uff08TextDecorder\u3092\u3053\u308c\u3067\u77e5\u308a\u307e\u3057\u305f\uff09<\/p>\n\n\n\n
tag_size = new DataView(mp4data.slice(pos,pos+4).buffer).getUint32(0,false);<\/p>\n\n\n\n
Dataview\u306farrayBuffer\u3058\u3083\u306a\u3044\u3068\u30c0\u30e1\u3089\u3057\u3044\u306e\u3067<\/p>\n\n\n\n
\n
mp4data.slice(pos,pos+4).buffer<\/p>\n<\/blockquote>\n\n\n\n
\u3053\u3053\u3089\u3078\u3093\u306e\u51e6\u7406\u306fUint8Array\u3092arrayBuffer\u306b\u3057\u3066\u307e\u3059\u3002<\/p>\n\n\n\n
\n
getUint32(0,false);
mp4\u306e\u30bf\u30b0\u306e\u6570\u5b57\u306f\u30d3\u30c3\u30b0\u30a8\u30f3\u30c7\u30a3\u30a2\u30f3\u306a\u306e\u3067\u6307\u5b9a\u3057\u3066\u3044\u307e\u3059\u3002
\u3053\u308c\u3067\u30b9\u30e0\u30fc\u30ba\u306b\u30d1\u30fc\u30b9\u51fa\u6765\u307e\u3057\u305f\u3002<\/p>\n<\/blockquote>\n\n\n\n
\u3061\u306a\u307f\u306b\u51fa\u529b\u3059\u308b\u3068\u3053\u3093\u306a\u611f\u3058\u3067\u3059\u3002<\/p>\n\n\n\n
ftyp
moov
-mvhd
-trak
–tkhd
–mdia
—mdhd
—hdlr
—minf
—-smhd
—-dinf
—–dref
—-stbl
—–stsd
—–stts
—–stsc
—–stsz
—–stco
-mvex
–trex
moof
-mfhd
-traf
–tfhd
–tfdt
–trun
mdat<\/p>\n\n\n\n
\u4e0d\u7d30\u5de5\u306a\u4f5c\u308a\u3067\u3059\u304c\u3068\u308a\u3042\u3048\u305a\u51fa\u529b\u3055\u308c\u308b\u306e\u3067\u826f\u3044\u306e\u304b\u306a\u3068\u3002
\u5fc5\u8981\u306b\u5fdc\u3058\u3066\u5404\u30bf\u30b0\u3067\u51e6\u7406\u3092\u5165\u308c\u3066\u3044\u304f\u306e\u3067\u3059\u304cchatgpt\u306a\u3069\u3067\u8abf\u3079\u3066\u30a2\u30ec\u30f3\u30b8\u3059\u308b\u3068\u697d\u3057\u3044\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u3002<\/p>\n\n\n\n
\u6587\uff1a\u958b\u767a\u30b9\u30bf\u30c3\u30d5AH<\/p>\n","protected":false},"excerpt":{"rendered":"
\u958b\u767a\u30b9\u30bf\u30c3\u30d5AH\u3067\u3059\u3002 \u5148\u65e5Chrome\u306b\u3066Mediarecorder\u3092\u30b3\u30fc\u30c7\u30c3\u30afMP4\u6307\u5b9a\u3067\u884c\u3063\u305f\u3068\u3053\u308d\u3001\u6307\u5b9a\u3057\u305f\u6570\u5024\u3068\u7570\u306a\u3063\u305f\u79d2\u6570\u3067\u30e1\u30c7\u30a3\u30a2\u3092\u5207\u308a\u51fa\u3057\u3066\u304d\u305f\u4e8b\u4ef6\u304c\u3042\u308a\u307e\u3057\u305f\u3002\u7279\u306b\u30a8\u30e9\u30fc\u3082\u7121\u3057\u3060\u3063\u305f\u306e\u3067\u3053\u308c\u304c\u4ed5\u69d8\u3068\u306a\u308b […]<\/p>\n","protected":false},"author":3,"featured_media":5119,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[31],"tags":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/zeoninc.com\/blog\/wp-json\/wp\/v2\/posts\/5118"}],"collection":[{"href":"https:\/\/zeoninc.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/zeoninc.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/zeoninc.com\/blog\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/zeoninc.com\/blog\/wp-json\/wp\/v2\/comments?post=5118"}],"version-history":[{"count":2,"href":"https:\/\/zeoninc.com\/blog\/wp-json\/wp\/v2\/posts\/5118\/revisions"}],"predecessor-version":[{"id":5123,"href":"https:\/\/zeoninc.com\/blog\/wp-json\/wp\/v2\/posts\/5118\/revisions\/5123"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/zeoninc.com\/blog\/wp-json\/wp\/v2\/media\/5119"}],"wp:attachment":[{"href":"https:\/\/zeoninc.com\/blog\/wp-json\/wp\/v2\/media?parent=5118"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zeoninc.com\/blog\/wp-json\/wp\/v2\/categories?post=5118"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zeoninc.com\/blog\/wp-json\/wp\/v2\/tags?post=5118"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}