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• Avconv : Select german stream not highest quality one

  15 novembre 2013, par mblaettermann

  I am converting some input stream from my DVB S2 Card to RTMP.

  Everything works fine after switching to recent avconv and x264 :)

  The only thing I couldn't find out is, how do I select the right audio stream ?

  The source sometimes has up to 6 audio tracks. Avconv automatically chooses the one with the highest bitrate. However I want to select the "ger" one :

  Here are the streams of ARTE german/french TV Channel for example :

  Input #0, mpegts, from 'http://192.168.1.50:9981/stream/channelid/1035':
  
    Duration: N/A, start: 19083.694722, bitrate: 15576 kb/s
  
    Program 1
  
      Stream #0.0[0xa8], 127, 1/90000: Video: mpeg2video (Main), yuv420p, 544x576 [PAR 32:17 DAR 16:9], 1/50, 15000 kb/s, 25 fps, 90k tb50 tbc
  
      Stream #0.1[0x70](fre), 204, 1/90000: Audio: mp2, 48000 Hz, stereo, s16p, 192 kb/s
  
      Stream #0.2[0x71](ger), 207, 1/90000: Audio: mp2, 48000 Hz, stereo, s16p, 128 kb/s
  
      Stream #0.3[0x72](eng), 207, 1/90000: Audio: mp2, 48000 Hz, stereo, s16p, 128 kb/s
  
      Stream #0.4[0x73](qaa), 207, 1/90000: Audio: mp2, 48000 Hz, stereo, s16p, 128 kb/s
  
    No Program
  
      Stream #0.5[0x3b], 126, 1/90000: Audio: mp1, 0 channels, s16p

  libav Docs are really not that helpful. Who does now the right syntax ?

  EDIT : I found the -map option : http://ffmpeg.org/trac/ffmpeg/wiki/How%20to%20use%20-map%20option But it is not possible to map by name ? Only by index ?

  Maybe I need to use avprobe then, to find the corrent stream index for "ger".

• Audio PTS is not equal but play time is equal

  20 juillet 2023, par KaGa Wu

  I have a video which has an dubbed Portuguese audio stream. The stream does not have the video head, like BGM of companies playing logos. So, the audio stream to delay some time play, it's first data package PTS is 9s. Then I transcode the audio stream to AAC, it's first package PTS is 2s. In my thinking the audio stream put the first data package in more front, it will play in more front originally, but it plays delay time is right !

  


  Here is the first package PTS, origin and transcoded.

  


  origin

  


  https://files.videohelp.com/u/302682/025_sisu_hevc_1920x800_30s_yuv420p_aac_copy.ts

  


  0x00458B74 Transport Packet { PID = 0x101, Payload = Yes (182), Counter = 15, Start indicator }
Adaptation Field ():
adaptation_field_length = 1
discontinuity_indicator = 0
random_access_indicator = 1
elementary_stream_priority_indicator = 0
PCR_flag = 0
OPCR_flag = 0
splicing_point_flag = 0
transport_private_data_flag = 0
adaptation_field_extension_flag = 0

0x00458B7A PES Packet { stream_id = 0xC0  (audio stream)}
packet_length = 2898
PES_scrambling_control = 0
PES_priority = 0
data_alignment_indicator = 0
copyright = 0
original_or_copy = 0
PTS_DTS_flags = 2
ESCR_flag = 0
ES_rate_flag = 0
DSM_trick_mode_flag = 0
additional_copy_info_flag = 0
PES_CRC_flag = 0
PES_extension_flag = 0
PES_header_data_length = 5
 PTS =  0:  0:  9: 570 (861 300)

0x00458B88 AAC Frame
id = 0
layer = 0
protection_absent = 1
profile = 1
sf_index = 3
private_bit = 0
channel_configuration = 6
original = 0
home = 0
copyright_identification_bit = 0
copyright_identification_start = 0
aac_frame_length = 285
adts_buffer_fullness = 2047
no_raw_data_blocks_in_frame = 0
SamplingRate = 48000
Channels = 6
Duration = 0.021333


  


  transcoded

  


  https://files.videohelp.com/u/302682/025_susi_hevc_1920x800_30s_yuv420p_aac_trans.ts

  


  0x000010E4 Transport Packet { PID = 0x101, Payload = Yes (182), Counter = 0, Start indicator }
Adaptation Field ():
adaptation_field_length = 1
discontinuity_indicator = 0
random_access_indicator = 1
elementary_stream_priority_indicator = 0
PCR_flag = 0
OPCR_flag = 0
splicing_point_flag = 0
transport_private_data_flag = 0
adaptation_field_extension_flag = 0

0x000010EA PES Packet { stream_id = 0xC0  (audio stream)}
packet_length = 467
PES_scrambling_control = 0
PES_priority = 0
data_alignment_indicator = 0
copyright = 0
original_or_copy = 0
PTS_DTS_flags = 2
ESCR_flag = 0
ES_rate_flag = 0
DSM_trick_mode_flag = 0
additional_copy_info_flag = 0
PES_CRC_flag = 0
PES_extension_flag = 0
PES_header_data_length = 5
 PTS =  0:  0:  1: 400 (126 000)

0x000010F8 AAC Frame
id = 0
layer = 0
protection_absent = 1
profile = 1
sf_index = 3
private_bit = 0
channel_configuration = 6
original = 0
home = 0
copyright_identification_bit = 0
copyright_identification_start = 0
aac_frame_length = 43
adts_buffer_fullness = 2047
no_raw_data_blocks_in_frame = 0
SamplingRate = 48000
Channels = 6
Duration = 0.021333


  


  I decode the origin video and transcoded video，and print screen of them.

  


• Streaming audio from mac with ffmpeg to nginx and playback with videojs

  15 juillet 2020, par Disco Fever

  I'm playing around trying to get to stream my Mac's sound to a webpage.

  


  Here's what I have so far :

  


  On the mac :

  


  ffmpeg -f avfoundation -i ":2" -acodec libmp3lame -ab32k -ac 1 -f flv rtmp://myserver:8000/hls/live


  


  On the nginx side :

  


  events {
    worker_connections  1024;
}

rtmp {
    server {
        listen 8000;
        chunk_size 4000;
        application hls {
            live on;
            interleave on;
            hls on;
            hls_path /tmp/hls;
        }
    }
}

http {
    default_type  application/octet-stream;
    sendfile off;
    tcp_nopush on;
    server {

        listen      8080;
        location /hls {
            add_header Cache-Control no-cache;
            types {
                application/vnd.apple.mpegurl m3u8;
                video/mp2t ts;
            }
            root /tmp;
        }
    }
}


  


  Web side :

  


  &#xA;&#xA;&#xA;    &#xA;    &#xA;&#xA;<code class="echappe-js">&lt;script src=&quot;//vjs.zencdn.net/7.8.2/video.min.js&quot;&gt;&lt;/script&gt;&#xA;&#xA;&#xA;&#xA;&#xA;&#xA;

  


  No matter what i do I can't get any sound (it's playing on the Mac 100% sure) ; i've tried also putting a video tag instead, i see the image but no sound. What's missing here ? Can this even be achieved ?

  


  THanks