ffmpeg copyts per conservare timestamp

Question

Sto tentando di modificare un flusso di trasporto del segmento HLS e di preservare l'ora di inizio con ffmpeg. Tuttavia, l'output non conserva il valore start_time del file di input, anche se viene menzionato -copyts. Ecco la mia linea di comando:

ffmpeg -i fileSequence1.ts -i x.png -filter_complex '[0:v][1:v]overlay[out]' -map '[out]' -map 0:1 -acodec copy -vsync 0 -vcodec libx264 -streamid 0:257 -streamid 1:258 -copyts -profile:v baseline -level 3 output.ts 

Il valore start_time è ritardato circa 2 secondi in modo coerente.

/Users/macadmin/>ffmpeg -y -v verbose -i fileSequence0.ts -map 0:0 -vcodec libx264 -copyts -vsync 0 -async 0 output.ts 
ffmpeg version 2.5.3 Copyright (c) 2000-2015 the FFmpeg developers 
    built on Mar 29 2015 21:31:57 with Apple LLVM version 6.0 (clang-600.0.54) (based on LLVM 3.5svn) 
    configuration: --prefix=/usr/local/Cellar/ffmpeg/2.5.3 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-libx264 --enable-libmp3lame --enable-libvo-aacenc --enable-libxvid --enable-libfreetype --enable-libvorbis --enable-libvpx --enable-libass --enable-ffplay --enable-libfdk-aac --enable-libopus --enable-libquvi --enable-libx265 --enable-nonfree --enable-vda 
    libavutil  54. 15.100/54. 15.100 
    libavcodec  56. 13.100/56. 13.100 
    libavformat 56. 15.102/56. 15.102 
    libavdevice 56. 3.100/56. 3.100 
    libavfilter  5. 2.103/5. 2.103 
    libavresample 2. 1. 0/2. 1. 0 
    libswscale  3. 1.101/3. 1.101 
    libswresample 1. 1.100/1. 1.100 
    libpostproc 53. 3.100/53. 3.100 
[h264 @ 0x7fa93b800000] Current profile doesn't provide more RBSP data in PPS, skipping 
    Last message repeated 2 times 
[mpegts @ 0x7fa93a80da00] max_analyze_duration 5000000 reached at 5000000 microseconds 
Input #0, mpegts, from 'fileSequence0.ts': 
    Duration: 00:00:09.65, start: 9.952111, bitrate: 412 kb/s 
    Program 1 
    Stream #0:0[0x101]: Video: h264 (Constrained Baseline) ([27][0][0][0]/0x001B), yuv420p, 640x360 (640x368), 25 fps, 25 tbr, 90k tbn, 50 tbc 
    Stream #0:1[0x102]: Audio: aac (LC) ([15][0][0][0]/0x000F), 44100 Hz, stereo, fltp, 101 kb/s 
[graph 0 input from stream 0:0 @ 0x7fa93a5229c0] w:640 h:360 pixfmt:yuv420p tb:1/90000 fr:25/1 sar:0/1 sws_param:flags=2 
[libx264 @ 0x7fa93b800c00] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX 
[libx264 @ 0x7fa93b800c00] profile High, level 3.0 
[mpegts @ 0x7fa93b800600] muxrate VBR, pcr every 2 pkts, sdt every 200, pat/pmt every 40 pkts 
Output #0, mpegts, to 'output.ts': 
    Metadata: 
    encoder   : Lavf56.15.102 
    Stream #0:0: Video: h264 (libx264), yuv420p, 640x360, q=-1--1, 25 fps, 90k tbn, 25 tbc 
    Metadata: 
     encoder   : Lavc56.13.100 libx264 
Stream mapping: 
    Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264)) 
Press [q] to stop, [?] for help 
[NULL @ 0x7fa93b800000] Current profile doesn't provide more RBSP data in PPS, skipping 
    Last message repeated 1 times 
frame= 87 fps=0.0 q=28.0 size=  91kB time=00:00:11.40 bitrate= 65.0kbits/[NULL @ 0x7fa93b800000] Current profile doesn't provide more RBSP data in PPS, skipping 
frame= 152 fps=151 q=28.0 size=  204kB time=00:00:14.00 bitrate= 119.4kbits/[NULL @ 0x7fa93b800000] Current profile doesn't provide more RBSP data in PPS, skipping 
frame= 224 fps=148 q=28.0 size=  306kB time=00:00:16.88 bitrate= 148.5kbits/No more output streams to write to, finishing. 
frame= 240 fps=125 q=-1.0 Lsize=  392kB time=00:00:19.52 bitrate= 164.6kbits/s  
video:334kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 17.347548% 
Input file #0 (fileSequence0.ts): 
    Input stream #0:0 (video): 240 packets read (360450 bytes); 240 frames decoded; 
    Input stream #0:1 (audio): 0 packets read (0 bytes); 
    Total: 240 packets (360450 bytes) demuxed 
Output file #0 (output.ts): 
    Output stream #0:0 (video): 240 frames encoded; 240 packets muxed (342204 bytes); 
    Total: 240 packets (342204 bytes) muxed 
[libx264 @ 0x7fa93b800c00] frame I:3  Avg QP:15.08 size: 7856 
[libx264 @ 0x7fa93b800c00] frame P:81 Avg QP:21.03 size: 2807 
[libx264 @ 0x7fa93b800c00] frame B:156 Avg QP:23.40 size: 585 
[libx264 @ 0x7fa93b800c00] consecutive B-frames: 11.7% 2.5% 7.5% 78.3% 
[libx264 @ 0x7fa93b800c00] mb I I16..4: 57.4% 17.5% 25.1% 
[libx264 @ 0x7fa93b800c00] mb P I16..4: 8.0% 8.2% 1.0% P16..4: 30.5% 11.3% 4.6% 0.0% 0.0% skip:36.4% 
[libx264 @ 0x7fa93b800c00] mb B I16..4: 0.1% 0.1% 0.0% B16..8: 34.6% 2.7% 0.2% direct: 1.3% skip:60.9% L0:47.3% L1:49.1% BI: 3.6% 
[libx264 @ 0x7fa93b800c00] 8x8 transform intra:42.2% inter:73.3% 
[libx264 @ 0x7fa93b800c00] coded y,uvDC,uvAC intra: 26.2% 43.0% 6.8% inter: 5.4% 8.5% 0.1% 
[libx264 @ 0x7fa93b800c00] i16 v,h,dc,p: 46% 26% 6% 21% 
[libx264 @ 0x7fa93b800c00] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 50% 14% 23% 1% 2% 6% 1% 3% 1% 
[libx264 @ 0x7fa93b800c00] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 40% 32% 10% 3% 3% 4% 2% 5% 2% 
[libx264 @ 0x7fa93b800c00] i8c dc,h,v,p: 48% 23% 26% 3% 
[libx264 @ 0x7fa93b800c00] Weighted P-Frames: Y:1.2% UV:0.0% 
[libx264 @ 0x7fa93b800c00] ref P L0: 71.5% 10.7% 14.8% 2.9% 0.1% 
[libx264 @ 0x7fa93b800c00] ref B L0: 95.5% 4.0% 0.5% 
[libx264 @ 0x7fa93b800c00] ref B L1: 96.8% 3.2% 
[libx264 @ 0x7fa93b800c00] kb/s:285.17 

----------- FFProbe source video 
/Users/macadmin>ffprobe fileSequence0.ts 
ffprobe version 2.5.3 Copyright (c) 2007-2015 the FFmpeg developers 
    built on Mar 29 2015 21:31:57 with Apple LLVM version 6.0 (clang-600.0.54) (based on LLVM 3.5svn) 
    configuration: --prefix=/usr/local/Cellar/ffmpeg/2.5.3 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-libx264 --enable-libmp3lame --enable-libvo-aacenc --enable-libxvid --enable-libfreetype --enable-libvorbis --enable-libvpx --enable-libass --enable-ffplay --enable-libfdk-aac --enable-libopus --enable-libquvi --enable-libx265 --enable-nonfree --enable-vda 
    libavutil  54. 15.100/54. 15.100 
    libavcodec  56. 13.100/56. 13.100 
    libavformat 56. 15.102/56. 15.102 
    libavdevice 56. 3.100/56. 3.100 
    libavfilter  5. 2.103/5. 2.103 
    libavresample 2. 1. 0/2. 1. 0 
    libswscale  3. 1.101/3. 1.101 
    libswresample 1. 1.100/1. 1.100 
    libpostproc 53. 3.100/53. 3.100 
Input #0, mpegts, from 'fileSequence0.ts': 
    Duration: 00:00:09.65, start: 9.952111, bitrate: 412 kb/s 
    Program 1 
    Stream #0:0[0x101]: Video: h264 (Constrained Baseline) ([27][0][0][0]/0x001B), yuv420p, 640x360, 25 fps, 25 tbr, 90k tbn, 50 tbc 
    Stream #0:1[0x102]: Audio: aac (LC) ([15][0][0][0]/0x000F), 44100 Hz, stereo, fltp, 101 kb/s 

------ FFPROBE result video 
/Users/macadmin>ffprobe output.ts 
ffprobe version 2.5.3 Copyright (c) 2007-2015 the FFmpeg developers 
    built on Mar 29 2015 21:31:57 with Apple LLVM version 6.0 (clang-600.0.54) (based on LLVM 3.5svn) 
    configuration: --prefix=/usr/local/Cellar/ffmpeg/2.5.3 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-libx264 --enable-libmp3lame --enable-libvo-aacenc --enable-libxvid --enable-libfreetype --enable-libvorbis --enable-libvpx --enable-libass --enable-ffplay --enable-libfdk-aac --enable-libopus --enable-libquvi --enable-libx265 --enable-nonfree --enable-vda 
    libavutil  54. 15.100/54. 15.100 
    libavcodec  56. 13.100/56. 13.100 
    libavformat 56. 15.102/56. 15.102 
    libavdevice 56. 3.100/56. 3.100 
    libavfilter  5. 2.103/5. 2.103 
    libavresample 2. 1. 0/2. 1. 0 
    libswscale  3. 1.101/3. 1.101 
    libswresample 1. 1.100/1. 1.100 
    libpostproc 53. 3.100/53. 3.100 
Input #0, mpegts, from 'output.ts': 
    Duration: 00:00:09.60, start: 11.400000, bitrate: 334 kb/s 
    Program 1 
    Metadata: 
     service_name : Service01 
     service_provider: FFmpeg 
    Stream #0:0[0x100]: Video: h264 (High) ([27][0][0][0]/0x001B), yuv420p, 640x360, 25 fps, 25 tbr, 90k tbn, 50 tbc 

Come posso garantire che file di output ha la stessa start_time? Grazie.

Answer 1

Ho deciso di scavare un po 'nella fonte per capire cosa sta succedendo.

• La start_time complessivo del programma è calcolato dalla utilizzando il timbro di tempo di presentazione (PTS) di ogni singolo flusso nel file.

• ffmpeg imposta un valore di ritardo decodifica Mux predefinito di 0,7 secondi. Questo è impostato nel ffmpeg_opt.c

  valore

Questo ritardo viene aggiunto al valore PTS di ciascun pacchetto, se il flag "copyts" non è impostato (nella libavformat/mpegtsenc.c):

if (ts->copyts < 1) { 
    if (pts != AV_NOPTS_VALUE) 
     pts += delay; 
    if (dts != AV_NOPTS_VALUE) 
     dts += delay; 
} 

In questo caso, l'encoder raddoppia il valore di ritardo:

const uint64_t delay = 
    av_rescale(s->max_delay, 90000, AV_TIME_BASE)*2; 

Pertanto, un extra di 1,4 secondi vengono aggiunti al PTS di ogni pacchetto. Se viene fornito "copyts", questo viene aggiunto al valore di timestamp dal flusso di input.

È possibile ignorare questo ritardo utilizzando il flag "muxdelay"; in tal caso il ritardo si azzera.

Ora, perché 0.7? perché due volte nel caso di mpeg ts? Vorrei sapere le risposte, presumibilmente è lì nelle specifiche da qualche parte. Ma per ora, questo dovrebbe fare.