一、问题描述
最近测试反馈一个隐私模式的问题，主播端启用隐私模式之后，在观看端发现画面转菊花并且还有回跳的现象
二、问题分析：
从网上下载了直播的视频文件，进行了一下分析，发现视频长度和音频长度不匹配，视频只有2分钟，音频有8分钟
怀疑是视频编码失败导致，因为没有log，不能够确认当时的情况，现在将排查的一些过程记录下
LUNLI-MC1:隐私模式问题排查 lunli$ ffprobe playlist-playlist.mp4
ffprobe version 3.4 Copyright (c) 2007-2017 the FFmpeg developers
built with Apple LLVM version 9.0.0 (clang-900.0.38)
configuration: --prefix=/usr/local/Cellar/ffmpeg/3.4 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-gpl --enable-ffplay --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma
libavutil 55. 78.100 / 55. 78.100
libavcodec 57.107.100 / 57.107.100
libavformat 57. 83.100 / 57. 83.100
libavdevice 57. 10.100 / 57. 10.100
libavfilter 6.107.100 / 6.107.100
libavresample 3. 7. 0 / 3. 7. 0
libswscale 4. 8.100 / 4. 8.100
libswresample 2. 9.100 / 2. 9.100
libpostproc 54. 7.100 / 54. 7.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'playlist-playlist.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf57.83.100
Duration: 00:07:30.64, start: 0.000000, bitrate: 156 kb/s
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuvj420p(pc), 1136x640, 395 kb/s, 21.30 fps, 90k tbr, 90k tbn, 180k tbc (default)
Metadata:
handler_name : VideoHandler
Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 9 kb/s (default)
Metadata:
handler_name : SoundHandler
LUNLI-MC1:隐私模式问题排查 lunli$ mp4box -info playlist-playlist.mp4
* Movie Info *
Timescale 1000 - 2 tracks
Computed Duration 00:07:30.644 - Indicated Duration 00:07:30.635
Fragmented File: no
File Brand isom - version 512
Compatible brands: isom iso2 avc1 mp41
Created: UNKNOWN DATE Modified: UNKNOWN DATE
File has no MPEG4 IOD/OD
iTunes Info:
Encoder Software: Lavf57.83.100
1 UDTA types: meta (1)
Track # 1 Info - TrackID 1 - TimeScale 90000
Media Duration 00:02:41.526 - Indicated Duration 00:02:41.526
Track has 1 edit lists: track duration is 00:02:41.527
Media Info: Language "Undetermined (und)" - Type "vide:avc1" - 3441 samples
Visual Track layout: x=0 y=0 width=1136 height=640
MPEG-4 Config: Visual Stream - ObjectTypeIndication 0x21
AVC/H264 Video - Visual Size 1136 x 640
AVC Info: 1 SPS - 1 PPS - Profile High @ Level 3.1
NAL Unit length bits: 32
Chroma format YUV 4:2:0 - Luma bit depth 8 - chroma bit depth 8
SPS#1 hash: E00BB071FEBC7AB23BDF361BA3FDC361F6B6CB76
PPS#1 hash: 846C70462484FB50AF3D7777307A8158D2D5AB5E
Self-synchronized
RFC6381 Codec Parameters: avc1.64001F
Average GOP length: 66 samples
Track # 2 Info - TrackID 2 - TimeScale 44100
Media Duration 00:07:30.634 - Indicated Duration 00:07:30.634
Track has 2 edit lists: track duration is 00:07:30.644
Media Info: Language "Undetermined (und)" - Type "soun:mp4a" - 19441 samples
MPEG-4 Config: Audio Stream - ObjectTypeIndication 0x40
MPEG-4 Audio AAC LC - 1 Channel(s) - SampleRate 44100
Synchronized on stream 1
RFC6381 Codec Parameters: mp4a.40.2
Alternate Group ID 1
All samples are sync