一、需求
通过脚本，可以检查本地flv文件格式是否正确，可以打印每个Tag中的二进制内容
二、效果
可以看到VideoTag中开始处增加了一段SEI数据，并且可以看到部分字段，gameid、time、network
三、实施
1）为了不重复造轮子，利用python下面的flvlib库
可以通过 pip install flvlib来安装，需要注意的是这个库工作在python2下面的环境
2）写一段代码，可以打印出flv中所有的tag
1import sys 2import logging 3 4from optparse import OptionParser 5 6from flvlib import __versionstr__ 7from flvlib import tags 8from flvlib import helpers 9from flvlib.astypes import MalformedFLV 10from array import array 11import HexTest 12 13 14class Packet: 15 16 def __init__(self, f, offset, size): 17 self.f = f 18 self.offset = offset 19 self.size = size 20 self.data = None 21 self.load() 22 23 24 def load(self): 25 cur_offset = f.tell() 26 f.seek(self.offset, 0) 27 self.data = f.read(self.size) 28 f.seek(cur_offset, 0) 29 self.prety_dump() 30 31 32 def prety_dump(self): 33 HexTest.dump_memory(array('B', self.data), self.offset) 34 35 36 37 38 39 40 41 42if __name__ == '__main__': 43 filename = "test4.flv" 44 with open(filename, 'rb') as f: 45 open(filename, 'rb') 46 47 flv = tags.FLV(f) 48 49 try: 50 tag_generator = flv.iter_tags() 51 print(flv.f.tell()) 52 for i, tag in enumerate(tag_generator): 53 # Print the tag information 54 print("#%05d %s" % (i + 1, tag)) 55 # Print the content of onMetaData tags 56 if (isinstance(tag, tags.ScriptTag) 57 and tag.name == "onMetaData"): 58 helpers.pprint(tag.variable) 59 print(str(type(tag))) 60 if isinstance(tag, tags.VideoTag) and (tag.frame_type == 1): 61 p = Packet(flv.f, tag.offset, tag.size) 62 63 64 except MalformedFLV as e: 65 message = e[0] % e[1:] 66 print("The file `%s' is not a valid FLV file: %s", 67 filename, message) 68 except tags.EndOfFile: 69 print("Unexpected end of file on file `%s'", filename)
main中的方法能够输出所有Tag，同时能够检查FLV文件是否正常
1#00672 <AudioTag at offset 0x001DD15B, time 9842, size 163, AAC, raw> 2<class 'flvlib.tags.AudioTag'> 3#00673 <VideoTag at offset 0x001DD20D, time 9855, size 11404, H.264 (interframe), NAL unit> 4<class 'flvlib.tags.VideoTag'> 5#00674 <AudioTag at offset 0x001DFEA8, time 9863, size 162, AAC, raw> 6<class 'flvlib.tags.AudioTag'> 7#00675 <AudioTag at offset 0x001DFF59, time 9884, size 168, AAC, raw> 8<class 'flvlib.tags.AudioTag'> 9#00676 <VideoTag at offset 0x001E0010, time 9903, size 6748, H.264 (interframe), NAL unit> 10<class 'flvlib.tags.VideoTag'> 11#00677 <AudioTag at offset 0x001E1A7B, time 9906, size 166, AAC, raw> 12<class 'flvlib.tags.AudioTag'> 13#00678 <AudioTag at offset 0x001E1B30, time 9927, size 159, AAC, raw> 14<class 'flvlib.tags.AudioTag'> 15#00679 <AudioTag at offset 0x001E1BDE, time 9948, size 162, AAC, raw> 16<class 'flvlib.tags.AudioTag'> 17#00680 <VideoTag at offset 0x001E1C8F, time 9950, size 8690, H.264 (interframe), NAL unit> 18<class 'flvlib.tags.VideoTag'> 19#00681 <AudioTag at offset 0x001E3E90, time 9970, size 166, AAC, raw> 20<class 'flvlib.tags.AudioTag'> 21#00682 <AudioTag at offset 0x001E3F45, time 9991, size 164, AAC, raw> 22<class 'flvlib.tags.AudioTag'> 23#00683 <VideoTag at offset 0x001E3FF8, time 9998, size 20543, H.264 (keyframe), NAL unit>
同时将每个Tag对应的开始位置和大小确定之后，读入内存中转成字节数组，并且格式化输出
1import sys 2import logging 3import struct 4from array import array 5 6 7def dump_newline(): 8 sys.stdout.write("\n") 9 10def dump_with_space(str): 11 sys.stdout.write(str + " ") 12 13def dump_line_number(x): 14 dump_with_space("%010xh:" % (x)) 15 16def dump_one_byte(x): 17 dump_with_space("%02x" % (x)) 18 19def dump_memory(data, memory_start_offset): 20 sys.stdout.flush() 21 start_line = (memory_start_offset/16)*16 22 for i in range(0, len(data), 16): 23 dump_line_number(i + start_line) 24 byte_arr = [] 25 for j in range(0, 16): 26 index = i + j 27 if index < len(data): 28 if (index + start_line) < memory_start_offset: 29 dump_with_space(" ") 30 else: 31 byte = data[index] 32 dump_one_byte(byte) 33 byte_arr.append(byte) 34 line_str = "; " + ("".join(map(chr, byte_arr))).replace('\n','').replace('\t','').replace('\r','') 35 dump_with_space(line_str) 36 dump_newline()
在代码中只针对VideoTag的IDR帧进行分析，并dump出数据