rtmpsave.c

#include <stdio.h>
#include <stdlib.h>
#include "librtmp/rtmp.h"

int main(int argc, char *argv[]) {
  if (argc < 3) {
    printf("usage : %s url ticket\n", argv[0]);
    return 1;
  }

  // initialize rtmp object
  RTMP *rtmp = RTMP_Alloc();
  if (rtmp == NULL) {
    printf("failed RTMP_Alloc\n");
    return 1;
  }
  RTMP_Init(rtmp);

  // build url (url must be non-constant string, so dynamically allocate memory)
  char url[1024];
  char *swfUrl = "http://live.nicovideo.jp/liveplayer.swf?20100531";
  sprintf(url, "%s conn=S:%s swfUrl=%s", argv[1], argv[2], swfUrl);
  printf("%s\n", url);

  RTMP_SetupURL(rtmp, url);
  if (!RTMP_Connect(rtmp, NULL)) {
    printf("failed to establish RTMP connection\n");
    return 1;
  }
  if (!RTMP_ConnectStream(rtmp, 0)) {
    printf("failed to establish RTMP session\n");
    return 1;
  }

  // open file
  FILE *fp = fopen("tmp.flv", "w+");
  if (fp == NULL) {
    printf("failed to open file\n");
    return 1;
  }

  // read stream and save to file
  long nRead;
  long size = 0;
  int bufsize = 64 * 1024;
  char *buf = (char *)malloc(bufsize);
  do {
    nRead = RTMP_Read(rtmp, buf, bufsize);
    if (nRead < 0) break; // success
    /*if (nRead == 0) {*/
      /*printf("chunk size is zero; fail?\n");*/
      /*break;*/
    /*}*/
    if (nRead != fwrite(buf, sizeof(char), nRead, fp)) {
      printf("failed to write to file\n");
      return 1;
    }
    size += nRead;
    if (nRead > 0)
      printf("total bytes read=%ld, chunk size=%ld, time=%.2fsec\n", size, nRead, (double)rtmp->m_read.timestamp/1000.0);
  } while(!RTMP_ctrlC && nRead > -1 && RTMP_IsConnected(rtmp));

  // finalize
  free(buf);
  fclose(fp);
  RTMP_Close(rtmp);
  RTMP_Free(rtmp);
  return 1;
}

コンパイル手順
MacPortsでrtmpdumpをインストールしてたら、

mkdir rtmpsave
cd rtmpsave
cp /opt/local/var/macports/distfiles/rtmpdump/rtmpdump-2.3.tgz .
tar xzf rtmpdump-2.3.tgz
cp -r rtmpdump-2.3/librtmp .
cd librtmp
make CRYPTO= SHARED=
cd ..

これでまずlibrtmpをコンパイルし、librtmp.aを作る。次に、

curl https://raw.github.com/gist/1463546/6e8cceaf0cfb2e1cbfb76b56e792691727b72df4/rtmpsave.c -o rtmpsave.c
gcc -c rtmpsave.c
gcc rtmpsave.o -L./librtmp -lrtmp -o rtmpsave

これでrtmpsave（実行ファイル）を作る。

使い方
まずニコニコ動画にログインしてセッションIDを取得

curl -k -D /dev/stdout -d mail=ほにゃらら -d password=ほにゃらら https://secure.nicovideo.jp/secure/login

次に、セッションIDをcookieとしてXMLを取得

curl -b user_session=user_session_ほにゃらら 'http://watch.live.nicovideo.jp/api/getplayerstatus?v=lvほにゃらら' -o tmp.xml

XMLから動画のURLとチケットを取得。

cat tmp.xml | sed 's/.*<quesheet>\(.*\)<\/quesheet>.*/\1/'
cat tmp.xml | sed 's/.*<ticket>\(.*\)<\/ticket>.*/\1/'

URLは例えば

rtmp://nlpoca02.live.nicovideo.jp:1935/fileorigin/ts_00,/content/20111211/lv73915381_094151546000_2_aa79cc.f4v?1323769877:30:52ae97da8354004f

みたいな感じなので、これの",/content"というところを"/mp4:content"に変える。最後にrtmpsaveを使う。

./rtmpsave "ユーアールエル" "チケット"

みたいな感じ。

↑をするためのRubyスクリプト

#!/usr/bin/env ruby

email = ""
password = ""

if ARGV.length < 1
  puts "usage: ruby rtmvsave.rb lv******** [cookie]"
  exit 1
end

cookie = nil

if ARGV.length == 2
  cookie = ARGV[1]
else
  cookie = nil
  header = `curl -k -D /dev/stdout -d mail=#{email} -d password=#{password} https://secure.nicovideo.jp/secure/login`
  if header =~ /(user_session=user_session_.*?);/
    cookie = $1
  end
end

exit 1 if cookie == nil

xml = `curl -b #{cookie} 'http://watch.live.nicovideo.jp/api/getplayerstatus?v=#{ARGV[0]}'`

url = nil
ticket = nil

if xml =~ /<que.*?(rtmp:\/\/.*?)<\/que>/
  url = $1.sub(",/content", "/mp4:content")
end

if xml =~ /<ticket>(.*?)<\/ticket>/
  ticket = $1
end

exit 1 if url == nil or ticket == nil

command = "./rtmpsave '#{url}' '#{ticket}'"
puts "running command:\n  #{command}"
system(command)

使い方は、メールとパスワードを入力して

ruby rtmvsave.rb lv********

と実行。