[FFmpeg-devel] how to download specific track data of a m3u8 content?
Halley Zhao
aihua.halley.zhao at gmail.com
Fri Jul 1 09:03:07 CEST 2016
I think I got the reason.
after I switch video track only, the audio and video track belongs to
different program; so both program are downloaded.
that means 4 track of stream (stream_index) reach me, though I select one
audio and one video track only.
I think it will be good to change audio track as well when video track is
changed, to use single program only.
2016-07-01 13:20 GMT+08:00 Halley Zhao <aihua.halley.zhao at gmail.com>:
> I tried ffplay on Ubuntu15.10, not expected result. seems buggy:
> ffplay.c, 3160, got packet with stream_index: 0
> ffplay.c, 3160, got packet with stream_index: 2
> ffplay.c, 3160, got packet with stream_index: 4
> ffplay.c, 3160, got packet with stream_index: 0
> ffplay.c, 3160, got packet with stream_index: 2
> ffplay.c, 3160, got packet with stream_index: 4
> ffplay.c, 3160, got packet with stream_index: 0
> ffplay.c, 3160, got packet with stream_index: 2
>
>
> 2016-07-01 9:22 GMT+08:00 Halley Zhao <aihua.halley.zhao at gmail.com>:
>
>> I tried it; but got unexpected result.
>> the pkt of discarded stream (stream_index) is still got from
>> av_read_frame().
>>
>> my code is here:
>> https://github.com/halleyzhao/player-ffmpeg-yami/blob/m3u8/player.c
>>
>> ## the code piece is here:
>> #define MAX_TRACK_COUNT 10
>> uint32_t video_tracks[MAX_TRACK_COUNT], video_track_count = 0;
>> uint32_t audio_tracks[MAX_TRACK_COUNT], audio_track_count = 0;
>> for (i = 0; i < pFormat->nb_streams; i++) {
>> if (pFormat->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
>> {
>> video_tracks[video_track_count++] = i;
>> } else if (pFormat->streams[i]->codec->codec_type ==
>> AVMEDIA_TYPE_AUDIO) {
>> audio_tracks[audio_track_count++] = i;
>> }
>> pFormat->streams[i]->discard = AVDISCARD_ALL;
>> }
>>
>> if (video_track_count) {
>> video_track_index = 0;
>> video_stream_index = video_tracks[video_track_index];
>> pFormat->streams[video_stream_index]->discard = AVDISCARD_DEFAULT;
>> }
>> if (audio_track_count) {
>> audio_track_index = 0;
>> audio_stream_index = audio_tracks[audio_track_index];
>> pFormat->streams[audio_stream_index]->discard = AVDISCARD_DEFAULT;
>> }
>> ## and the result is here: video track has index 0/2/4. when I set 0
>> stream to AVDISCARD_DEFAULT and 2/4 to AVDISCARDALL, the pkt with
>> stream_index 2/4 still reach me.
>> player.c, 114, got pkt with stream_index: 0
>> player.c, 114, got pkt with stream_index: 2
>> player.c, 114, got pkt with stream_index: 4
>> player.c, 114, got pkt with stream_index: 0
>> player.c, 114, got pkt with stream_index: 2
>> player.c, 114, got pkt with stream_index: 4
>> player.c, 114, got pkt with stream_index: 0
>> player.c, 114, got pkt with stream_index: 2
>> player.c, 114, got pkt with stream_index: 3
>> player.c, 114, got pkt with stream_index: 3
>> player.c, 114, got pkt with stream_index: 4
>> player.c, 114, got pkt with stream_index: 5
>> player.c, 114, got pkt with stream_index: 5
>>
>> 2016-06-29 19:25 GMT+08:00 aihua zhao <aihua.halley.zhao at gmail.com>:
>>
>>> thanks, seems the right clue to follow.
>>>
>>> I don't know much about ffmpeg, after went through avplay.c. I think I
>>> should do the following steps
>>> 1. discard all stream by default.
>>> refer to decode_thread()
>>> for (i = 0; i < ic->nb_streams; i++)
>>> ic->streams[i]->discard = AVDISCARD_ALL;
>>> 2. enable the desired stream only
>>> refer to stream_component_open()
>>> ic->streams[stream_index]->discard = AVDISCARD_DEFAULT;
>>>
>>> thanks for your help.
>>>
>>> 2016-06-29 10:01 GMT+08:00 Steven Liu <lingjiujianke at gmail.com>:
>>>
>>>> 2016-06-29 8:36 GMT+08:00 aihua zhao <aihua.halley.zhao at gmail.com>:
>>>>
>>>> > thanks.
>>>> >
>>>> > Yes, readahead the list is must.
>>>> > but during playback, I found ffmpeg downloads each content of the list
>>>> > -- av_read_frame() returns me each content with different
>>>> stream_index.
>>>> > I'm expecting av_read_frame() returns me the interested stream only.
>>>> > I haven't found a way to do so; or said, is there ffmpeg interface to
>>>> > specify a dedicate stream (stream_index) to download.
>>>> >
>>>> > i'm looking into hls.c; there is recheck_discard_flags(), seems it is
>>>> > designed to do some policy like this.
>>>> > but I haven't found one top level interface of ffmpeg for it.
>>>> > recheck_discard_flags() is called once only during hls_read_packet()
>>>> when
>>>> > c->first_packet is set -- this flag is set in hls_read_header() only.
>>>> >
>>>> >
>>>> > 2016-06-28 22:22 GMT+08:00 Steven Liu <lingjiujianke at gmail.com>:
>>>> >
>>>> > > 2016-06-28 14:26 GMT+08:00 aihua zhao <aihua.halley.zhao at gmail.com
>>>> >:
>>>> > >
>>>> > > > Hi Experts:
>>>> > > >
>>>> > > > I use ffmpeg to parse/demux media content, and created a player
>>>> basing
>>>> > on
>>>> > > > it.
>>>> > > >
>>>> > > > here is a m3u8 content:
>>>> > > >
>>>> > > >
>>>> > >
>>>> >
>>>> http://asp.cntv.lxdns.com/asp/hls/main/0303000a/3/default/438eb7a818b246c187e72f1cd4e1bc4c/main.m3u8
>>>> > > > <
>>>> > > >
>>>> > >
>>>> >
>>>> http://asp.cntv.lxdns.com/asp/hls/main/0303000a/3/default/438eb7a818b246c187e72f1cd4e1bc4c/main.m3u8?maxbr=1200
>>>> > > > >
>>>> > > > there are three video track in it.
>>>> > > >
>>>> > > > I found all video/audio tracks are downloaded during playback,
>>>> and I
>>>> > can
>>>> > > > switch different track on the fly.
>>>> > > > however, it consumes much bandwidth since all tracks are
>>>> downloaded.
>>>> > > >
>>>> > > > even when I append bandwidth to the url; still the same result:
>>>> > > >
>>>> > > >
>>>> > >
>>>> >
>>>> http://asp.cntv.lxdns.com/asp/hls/main/0303000a/3/default/438eb7a818b246c187e72f1cd4e1bc4c/main.m3u8?maxbr=1200
>>>> > > >
>>>> > > > Is there any way to download the specified track only to save
>>>> > bandwidth?
>>>> > > >
>>>> > > > thanks
>>>> > > >
>>>> > >
>>>> > > Hi Aihua Zhao,
>>>> > >
>>>> > > If you haven't read the m3u8 file and parse the playlist, and
>>>> read
>>>> > > the sub m3u8 playlist, how do you get the info of the mpegts?
>>>> > >
>>>> > > So it's must readahead the list and list all of the track for
>>>> > choose.
>>>> > you mean the function looks like "stream_cycle_channel" in ffplay?
>>>> >
>>>> _______________________________________________
>>>> ffmpeg-devel mailing list
>>>> ffmpeg-devel at ffmpeg.org
>>>> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>>>>
>>>
>>>
>>
>
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