17 ms·

FFmpeg 4.2

327 points by _Gyan_ 7y ago

antoineMoPa 7y ago
In case anyone is confused with FFmpeg, ffmpeg, libav. etc., follow [0]: [0] https://stackoverflow.com/questions/9477115/what-are-the-differences-and-similarities-between-ffmpeg-libav-and-avconv/9477756#9477756 https://stackoverflow.com/questions/9477115/what-are-the-dif...
- jaimex2 7y ago
  first I've heard of any of these. I've always just apt installed ffmpeg from my distro. Works perfectly.
  - Kaiyou 7y ago
    At some point in time that wouldn't have installed ffmpeg, but libav instead.
- Jaepa 7y ago
  So what is the difference? This comment looks to be adhomenum remarks on forks. If it’s clear and I’m just missing it, sorry i have a temp of 102.3 so I’m a little hazy.
  - anoncareer0212 7y ago
    TL;DR: Use ffmpeg Man, if these reads like ad hominem, I wish you could read the whole story. The linked comment is admirably restrained to the point it prefers being confusing over explaining what happened (fwiw I have no dog in the fight, was privy to the goings-on because my project depended on ffmpeg)
    - Jaepa 7y ago
      Alright. Got it thank you.
  - kuschku 7y ago
    Most of the core contributors had a fight with the project lead, so many of them left the project and forked into libav. So the community and the projects both split, and both fought about being the real one. And at first, ffmpeg focused only on features, regardless of code quality, while libav focused on clean code, even if that meant compromising on features. Obviously, people who aligned with the project lead, and people wondering why stuff suddenly didn’t work anymore, were fed up with libav. Even though it was a situation where libavs codebase was, compared to ffmpeg, much cleaner, similar to openssl vs libressl, but sacrificed a huge amount of functionality for that goal. EDIT: Rephrasing for accuracy
    - Hello71 7y ago
      I have no bone in this fight, but this is an egregiously terrible and biased summary. I will pick some of the most ridiculous points here to rebut, but a better summary could be found in literally any of the search results for "ffmpeg libav". > The project lead had a fight with all the other core contributors There was longstanding animosity between the project lead and other developers, due to a variety of reasons, mainly his dictatorial leadership style. > everyone but the lead left the project and forked into libav A small set of contributors with technical control over certain infrastructure removed the lead's access. > So the community and the projects both split, and both fought about being the real one. This contradicts your previous claim that "everyone but the lead left the project". > And at first, ffmpeg focused only on features, regardless of security, while libav focused on security and clean code, even if that meant compromising on features. This is ridiculous. libav did remove a large amount of code that was working, some of which may have been insecure or not designed well, but a lot of which was actually necessary for people's workflows and not "dead code" as they claimed. Moreover, ffmpeg had a significantly better security profile than libav due to actually patching bugs rather than waiting to do it right (which ffmpeg developers will argue was basically "doing it differently than ffmpeg"). > Even though it was a situation where libavs codebase was, compared to ffmpeg, much cleaner, similar to openssl vs libressl. It wasn't cleaner, just less. It became more and more "less" when ffmpeg gained new (well-designed) features, and libav refused to merge them just because they were not designed by libav.
minimaxir 7y ago
What exactly is the "GIF parser"? I thought FFmpeg already did GIF I/O.
- em3rgent0rdr 7y ago
  Don't know exactly, but https://trac.ffmpeg.org/ticket/1347 https://trac.ffmpeg.org/ticket/1347 looks like the ticket and http://git.videolan.org/?p=ffmpeg.git;a=commitdiff;h=8f66d46ce5f41be8084ad14061cec8f8e769d711 http://git.videolan.org/?p=ffmpeg.git;a=commitdiff;h=8f66d46... looks like the commit implementing it.
- sp332 7y ago
  Looking at comments on https://stackoverflow.com/questions/53460876/process-gif-using-ffmpeg-libraries-cant-find-parser-at-av-parser-init https://stackoverflow.com/questions/53460876/process-gif-usi... there was only a demuxer, no parser. I'm not sure why you'd need a parser but according to https://superuser.com/a/787073 https://superuser.com/a/787073 ffmpeg always treated GIFs as movies, so maybe this is a way to tell which GIFs are single images?
  - astrange 7y ago
    IIRC parsers let it reconstruct metadata from files that aren't muxed, or inaccurately muxed. For instance, you'd need one to read raw .h264 files properly into .mp4. Not sure how that would apply to GIF.
    - _Gyan_ 7y ago
      Parsers typically are used to correctly demarcate packet boundaries in (coded) bitstreams e.g. H.264 bitstream is partitioned into NAL units and the parser assembles all relevant units for a single frame/slice so that the decoder gets everything it needs to decode that sample, nothing more, nothing less.
      - astrange 7y ago
        Well I should hope it does more by now because that's not enough information to mux an H.264 stream. You need to recover PTS/DTS offsets, keyframe types, SPS, etc.
citrusui 7y ago
A little confused on what they mean by PCM-DVD encoder. Wasn't ffmpeg always able to do this?
- _Gyan_ 7y ago
  PCM-DVD has a specific way in how the channels are interleaved. For bit depths higher than 16, each sample is split so that the lowest byte is stored following the high bytes of all channels. There's also a 3-byte metadata which has to be prefixed to each packet. All of these steps could have been done via a bitstream filter but since the codec_id is different, this has to be done at the encoding stage.
  - citrusui 7y ago
    Thanks for the info! Is there any resource online that I can look into to learn more? I'm not certain I know how audio interleaving works.
    - _Gyan_ 7y ago
      See https://wiki.multimedia.cx/index.php/PCM#DVD_PCM https://wiki.multimedia.cx/index.php/PCM#DVD_PCM
yboris 7y ago
Massive "thank you" to FFmpeg for being an amazing tool. My app pivotally depends on FFmpeg extracting screenshots of videos for users to browse through: https://github.com/whyboris/Video-Hub-App https://github.com/whyboris/Video-Hub-App
- benbristow 7y ago
  If you're making money from it, why not donate for future development? http://ffmpeg.org/donations.html http://ffmpeg.org/donations.html
  - davidweatherall 7y ago
    This software is available for $3.50 through videohubapp.com $3.50 of every sale goes to the cost-effective charity Against Malaria Foundation. Appears to donate 100% straight to Charity by the looks of it.
    - eXpl0it3r 7y ago
      The text is rather confusing. Why not directly mention that the money is fully donated? It's great that the author likes supporting a charity/foundation, but as a customer, I would expect my money to be used to maintain and further develop the software I pay for. Having all the money directly getting donated, makes me slightly worry about longevity/maintenance of a product...
      - pingyong 7y ago
        Maybe if you buy something for $3.50 you should always be slightly worried about the longevity/maintenance of the product...
      - yboris 7y ago
        Author here. I need to clarify my messaging on the website: $3.50 gets donated with every purchase (even though after fees a $3.50 purchase results in about $3.00 going to my account). The people who choose to pay more (there are many!) cover the fees -- huge "thank you" to them. I'm releasing version 2 in the next 2 months: anyone who ever bought the software (700+ people) will get the download link in their email. I keep a log of all the donations: https://videohubapp.com/blog.html https://videohubapp.com/blog.html -- you can click to see the charity website log as well: https://www.againstmalaria.com/VideoHubApp https://www.againstmalaria.com/VideoHubApp Happy to answer any questions :)
danabrams 7y ago
Can't say I blame them for the removal of libndi-newtek, given the situation, but I wish FFMpeg (and gstreamer) had ndi support. Would love to see an open source NDI, but I know newtek will never allow it.
- jsight 7y ago
  That is actually really sad. I wonder what are the chances of someone reimplementing NDI support as FOSS?
  - danabrams 7y ago
    I don’t think it’s just an implementation problem. I think there are patent issues preventing this. Newtek should really bite the bullet and just open source, and make their money on the hardware.
    - huslage 7y ago
      I don’t think it has anything to do with patents. Anyone can use the library for free. NewTek just doesn’t want to open source the library.
      - seandougall 7y ago
        Even though they don’t charge for the library, they have a lot riding on the perception of the quality of their protocol. If they allow third party implementations and some of them suck, it might tarnish NDI’s image (and indirectly hurt them via the money they make on hardware). Edit: I’m certainly not arguing that any particular implementation does suck, just saying that I can see why they might want to protect IP they don’t make money from directly.
    - noir_lord 7y ago
      Patents aren’t as much of an issue on software outside the US so it’s theoretically doable legally, it would just be like the situation with mp3 etc, Americans would have to snag the packages hosted from outside the US.
josteink 7y ago
Nice to see improved HEVC 4:4:4 support in Linux.
saghul 7y ago
> AV1 decoding support through libdav1d Nice to see progress in the AV1 front!
rolltiide 7y ago
remember the dark ages when we had to actually care about codecs and which ones were installed at any given point in time?
- canada_dry 7y ago
  > remember the dark ages... BVLC.
  - lapnitnelav 7y ago
    Veni vidi vlc
- dguaraglia 7y ago
  Bwahaha, I still remember getting those 'codepacs' for Windows that'd install like 20 codecs at the same time, including one that was a thin wrapper around libav/ffmpeg. 99% sure half of those violated all kinds of EULAs and copyright issues.
  - rolltiide 7y ago
    > 99% sure half of those violated all kinds of EULAs and copyright issues. by the time you got there you were way past that point.
- ArlenBales 7y ago
  Yup.. K-Lite Codec Pack, CCCP, etc.
- fucking_tragedy 7y ago
  Chromecasts don't support MPEG-TS. Suddenly had to care about that the other day.
LAMike 7y ago
Is there any higher level libraries for JS that wrap FFmpeg commands cleaner? I'm building some software on using it is kind of cumbersome
- deleted 7y ago
  [deleted]
- evangow 7y ago
  I haven't used it, but I believe JIMP might work for you if you're looking for a JS solution to image manipulation https://github.com/oliver-moran/jimp https://github.com/oliver-moran/jimp
  - h1d 7y ago
    For images, you'd want to use a more performant 'sharp'. https://github.com/lovell/sharp https://github.com/lovell/sharp Benchmark https://sharp.pixelplumbing.com/en/stable/performance/ https://sharp.pixelplumbing.com/en/stable/performance/
- rationalthug 7y ago
  For node, there is https://github.com/fluent-ffmpeg/node-fluent-ffmpeg https://github.com/fluent-ffmpeg/node-fluent-ffmpeg.
- ryanbharvey 7y ago
  I've been working through this over the last year plus in node, and ended up deciding with my team earlier this year to build a library that makes this easier to understand and work with. It's early yet, and explicit I/O mapping is not quite there at the moment, but you're welcome to check it out. Feedback is welcome. https://tedconf.github.io/fessonia https://tedconf.github.io/fessonia
KuhlMensch 7y ago
Is there anything in the new release that would allow an encoder to be "motion-aware"? e.g. if the video is static, don't store any information. But if there is movement in the video, start storing frames etc WHY? I find myself recording lots of videos of me talking through code in an IDE. The screen mostly static, with some occasional the screen scrolling. The regular tradeoff-space afforded by CRF doesn't seem to get me the size results I believe are possible.
- quixoticelixer- 7y ago
  Encoders already do this to some extent, but that is the codecs job (AV1, H264 etc) not FFmpegs.
- slimscsi 7y ago
  Increase the key-frame interval
- hackcasual 7y ago
  This might be helpful: https://video.stackexchange.com/questions/24680/what-is-keyint-and-min-keyint-and-no-scenecut https://video.stackexchange.com/questions/24680/what-is-keyi... If you're storing video only for offline viewing with minimal seeking, you can increase the iframe seperation, but if you're streaming this video, you'll need to pay the cost of including iframes to allow clients to seek or recover from dropped packets.
  - nullwasamistake 7y ago
    This guy is totally right. When there's no change on screen a huge percentage of bandwidth is from iframes, essentially start over points for fast forward and network corruption. There's a tradeoff between skip/fast forward fidelity, streaming delay, and iframes. If you're not live streaming and don't care how easy it is to skip around the video increase the iframes inverval as much as you want and watch the bitrate melt away
  - astrange 7y ago
    If you're streaming, you don't need to implement full I-frames; instead you can do a kind of top-to-bottom rolling refresh. The video will be corrupt until the decoder catches up, but that's OK. This is mostly used for TV broadcasts where you don't want the whole keyframe to get lost because of some brief interference. It's also good because it lowers peak bandwidth per second.
thwythwy 7y ago
Does this play nice with Python youtube-dl? [1] [2]. I want to run a python script on my computer that captures youtube audio of certain government meetings without first having to dl the entire video and convert it (while doing a bunch of other stuff before and after automatically, all without me touching anything). [1] https://stackoverflow.com/questions/27473526/download-only-audio-from-youtube-video-using-youtube-dl-in-python-script https://stackoverflow.com/questions/27473526/download-only-a... [2] https://stackoverflow.com/questions/39665160/youtube-dl-python-script-postprocessing-error-ffmpeg-codecs-arent-being-recogn https://stackoverflow.com/questions/39665160/youtube-dl-pyth...
- icebraining 7y ago
  Unless you need to convert the audio format, I don't think you need ffmpeg at all - youtube-dl can just download the audio stream and save it to a file. Just list the available formats from a video and choose an audio-only format.
  - thwythwy 7y ago
    will try thank you
  - Nullabillity 7y ago
    Also, IIRC youtube-dl will automatically re-encode it using ffmpeg if you pick an unavailable format!
  - timendum 7y ago
    Insome cases youtube-dl downloads the content via ffmpeg, see [1] [1] https://github.com/ytdl-org/youtube-dl/blob/c3bcd206eb031de30179c88ac7acd806a477ceae/youtube_dl/downloader/__init__.py https://github.com/ytdl-org/youtube-dl/blob/c3bcd206eb031de3...
- A2017U1 7y ago
  youtube-dl -x <url> uses ffmpeg out of the box to extract mp3 audio from a video.
- 7y ago

327 points by _Gyan_ 7y ago

In case anyone is confused with FFmpeg, ffmpeg, libav. etc., follow [0]: [0] https://stackoverflow.com/questions/9477115/what-are-the-differences-and-similarities-between-ffmpeg-libav-and-avconv/9477756#9477756 https://stackoverflow.com/questions/9477115/what-are-the-dif...

jaimex2 7y ago
first I've heard of any of these. I've always just apt installed ffmpeg from my distro. Works perfectly.
- Kaiyou 7y ago
  At some point in time that wouldn't have installed ffmpeg, but libav instead.
Jaepa 7y ago
So what is the difference? This comment looks to be adhomenum remarks on forks. If it’s clear and I’m just missing it, sorry i have a temp of 102.3 so I’m a little hazy.
- anoncareer0212 7y ago
  TL;DR: Use ffmpeg Man, if these reads like ad hominem, I wish you could read the whole story. The linked comment is admirably restrained to the point it prefers being confusing over explaining what happened (fwiw I have no dog in the fight, was privy to the goings-on because my project depended on ffmpeg)
  - Jaepa 7y ago
    Alright. Got it thank you.
- kuschku 7y ago
  Most of the core contributors had a fight with the project lead, so many of them left the project and forked into libav. So the community and the projects both split, and both fought about being the real one. And at first, ffmpeg focused only on features, regardless of code quality, while libav focused on clean code, even if that meant compromising on features. Obviously, people who aligned with the project lead, and people wondering why stuff suddenly didn’t work anymore, were fed up with libav. Even though it was a situation where libavs codebase was, compared to ffmpeg, much cleaner, similar to openssl vs libressl, but sacrificed a huge amount of functionality for that goal. EDIT: Rephrasing for accuracy
  - Hello71 7y ago
    I have no bone in this fight, but this is an egregiously terrible and biased summary. I will pick some of the most ridiculous points here to rebut, but a better summary could be found in literally any of the search results for "ffmpeg libav". > The project lead had a fight with all the other core contributors There was longstanding animosity between the project lead and other developers, due to a variety of reasons, mainly his dictatorial leadership style. > everyone but the lead left the project and forked into libav A small set of contributors with technical control over certain infrastructure removed the lead's access. > So the community and the projects both split, and both fought about being the real one. This contradicts your previous claim that "everyone but the lead left the project". > And at first, ffmpeg focused only on features, regardless of security, while libav focused on security and clean code, even if that meant compromising on features. This is ridiculous. libav did remove a large amount of code that was working, some of which may have been insecure or not designed well, but a lot of which was actually necessary for people's workflows and not "dead code" as they claimed. Moreover, ffmpeg had a significantly better security profile than libav due to actually patching bugs rather than waiting to do it right (which ffmpeg developers will argue was basically "doing it differently than ffmpeg"). > Even though it was a situation where libavs codebase was, compared to ffmpeg, much cleaner, similar to openssl vs libressl. It wasn't cleaner, just less. It became more and more "less" when ffmpeg gained new (well-designed) features, and libav refused to merge them just because they were not designed by libav.

minimaxir 7y ago

What exactly is the "GIF parser"? I thought FFmpeg already did GIF I/O.

em3rgent0rdr 7y ago
Don't know exactly, but https://trac.ffmpeg.org/ticket/1347 https://trac.ffmpeg.org/ticket/1347 looks like the ticket and http://git.videolan.org/?p=ffmpeg.git;a=commitdiff;h=8f66d46ce5f41be8084ad14061cec8f8e769d711 http://git.videolan.org/?p=ffmpeg.git;a=commitdiff;h=8f66d46... looks like the commit implementing it.
sp332 7y ago
Looking at comments on https://stackoverflow.com/questions/53460876/process-gif-using-ffmpeg-libraries-cant-find-parser-at-av-parser-init https://stackoverflow.com/questions/53460876/process-gif-usi... there was only a demuxer, no parser. I'm not sure why you'd need a parser but according to https://superuser.com/a/787073 https://superuser.com/a/787073 ffmpeg always treated GIFs as movies, so maybe this is a way to tell which GIFs are single images?
- astrange 7y ago
  IIRC parsers let it reconstruct metadata from files that aren't muxed, or inaccurately muxed. For instance, you'd need one to read raw .h264 files properly into .mp4. Not sure how that would apply to GIF.
  - _Gyan_ 7y ago
    Parsers typically are used to correctly demarcate packet boundaries in (coded) bitstreams e.g. H.264 bitstream is partitioned into NAL units and the parser assembles all relevant units for a single frame/slice so that the decoder gets everything it needs to decode that sample, nothing more, nothing less.
    - astrange 7y ago
      Well I should hope it does more by now because that's not enough information to mux an H.264 stream. You need to recover PTS/DTS offsets, keyframe types, SPS, etc.

citrusui 7y ago

A little confused on what they mean by PCM-DVD encoder. Wasn't ffmpeg always able to do this?

_Gyan_ 7y ago
PCM-DVD has a specific way in how the channels are interleaved. For bit depths higher than 16, each sample is split so that the lowest byte is stored following the high bytes of all channels. There's also a 3-byte metadata which has to be prefixed to each packet. All of these steps could have been done via a bitstream filter but since the codec_id is different, this has to be done at the encoding stage.
- citrusui 7y ago
  Thanks for the info! Is there any resource online that I can look into to learn more? I'm not certain I know how audio interleaving works.
  - _Gyan_ 7y ago
    See https://wiki.multimedia.cx/index.php/PCM#DVD_PCM https://wiki.multimedia.cx/index.php/PCM#DVD_PCM

yboris 7y ago

Massive "thank you" to FFmpeg for being an amazing tool. My app pivotally depends on FFmpeg extracting screenshots of videos for users to browse through: https://github.com/whyboris/Video-Hub-App https://github.com/whyboris/Video-Hub-App

benbristow 7y ago
If you're making money from it, why not donate for future development? http://ffmpeg.org/donations.html http://ffmpeg.org/donations.html
- davidweatherall 7y ago
  This software is available for $3.50 through videohubapp.com $3.50 of every sale goes to the cost-effective charity Against Malaria Foundation. Appears to donate 100% straight to Charity by the looks of it.
  - eXpl0it3r 7y ago
    The text is rather confusing. Why not directly mention that the money is fully donated? It's great that the author likes supporting a charity/foundation, but as a customer, I would expect my money to be used to maintain and further develop the software I pay for. Having all the money directly getting donated, makes me slightly worry about longevity/maintenance of a product...
    - pingyong 7y ago
      Maybe if you buy something for $3.50 you should always be slightly worried about the longevity/maintenance of the product...
    - yboris 7y ago
      Author here. I need to clarify my messaging on the website: $3.50 gets donated with every purchase (even though after fees a $3.50 purchase results in about $3.00 going to my account). The people who choose to pay more (there are many!) cover the fees -- huge "thank you" to them. I'm releasing version 2 in the next 2 months: anyone who ever bought the software (700+ people) will get the download link in their email. I keep a log of all the donations: https://videohubapp.com/blog.html https://videohubapp.com/blog.html -- you can click to see the charity website log as well: https://www.againstmalaria.com/VideoHubApp https://www.againstmalaria.com/VideoHubApp Happy to answer any questions :)

danabrams 7y ago

Can't say I blame them for the removal of libndi-newtek, given the situation, but I wish FFMpeg (and gstreamer) had ndi support. Would love to see an open source NDI, but I know newtek will never allow it.

jsight 7y ago
That is actually really sad. I wonder what are the chances of someone reimplementing NDI support as FOSS?
- danabrams 7y ago
  I don’t think it’s just an implementation problem. I think there are patent issues preventing this. Newtek should really bite the bullet and just open source, and make their money on the hardware.
  - huslage 7y ago
    I don’t think it has anything to do with patents. Anyone can use the library for free. NewTek just doesn’t want to open source the library.
    - seandougall 7y ago
      Even though they don’t charge for the library, they have a lot riding on the perception of the quality of their protocol. If they allow third party implementations and some of them suck, it might tarnish NDI’s image (and indirectly hurt them via the money they make on hardware). Edit: I’m certainly not arguing that any particular implementation does suck, just saying that I can see why they might want to protect IP they don’t make money from directly.
  - noir_lord 7y ago
    Patents aren’t as much of an issue on software outside the US so it’s theoretically doable legally, it would just be like the situation with mp3 etc, Americans would have to snag the packages hosted from outside the US.

josteink 7y ago

Nice to see improved HEVC 4:4:4 support in Linux.

saghul 7y ago

> AV1 decoding support through libdav1d Nice to see progress in the AV1 front!

rolltiide 7y ago

remember the dark ages when we had to actually care about codecs and which ones were installed at any given point in time?

canada_dry 7y ago
> remember the dark ages... BVLC.
- lapnitnelav 7y ago
  Veni vidi vlc
dguaraglia 7y ago
Bwahaha, I still remember getting those 'codepacs' for Windows that'd install like 20 codecs at the same time, including one that was a thin wrapper around libav/ffmpeg. 99% sure half of those violated all kinds of EULAs and copyright issues.
- rolltiide 7y ago
  > 99% sure half of those violated all kinds of EULAs and copyright issues. by the time you got there you were way past that point.
ArlenBales 7y ago
Yup.. K-Lite Codec Pack, CCCP, etc.
fucking_tragedy 7y ago
Chromecasts don't support MPEG-TS. Suddenly had to care about that the other day.

LAMike 7y ago

Is there any higher level libraries for JS that wrap FFmpeg commands cleaner? I'm building some software on using it is kind of cumbersome

deleted 7y ago
[deleted]
evangow 7y ago
I haven't used it, but I believe JIMP might work for you if you're looking for a JS solution to image manipulation https://github.com/oliver-moran/jimp https://github.com/oliver-moran/jimp
- h1d 7y ago
  For images, you'd want to use a more performant 'sharp'. https://github.com/lovell/sharp https://github.com/lovell/sharp Benchmark https://sharp.pixelplumbing.com/en/stable/performance/ https://sharp.pixelplumbing.com/en/stable/performance/
rationalthug 7y ago
For node, there is https://github.com/fluent-ffmpeg/node-fluent-ffmpeg https://github.com/fluent-ffmpeg/node-fluent-ffmpeg.
ryanbharvey 7y ago
I've been working through this over the last year plus in node, and ended up deciding with my team earlier this year to build a library that makes this easier to understand and work with. It's early yet, and explicit I/O mapping is not quite there at the moment, but you're welcome to check it out. Feedback is welcome. https://tedconf.github.io/fessonia https://tedconf.github.io/fessonia

KuhlMensch 7y ago

Is there anything in the new release that would allow an encoder to be "motion-aware"? e.g. if the video is static, don't store any information. But if there is movement in the video, start storing frames etc WHY? I find myself recording lots of videos of me talking through code in an IDE. The screen mostly static, with some occasional the screen scrolling. The regular tradeoff-space afforded by CRF doesn't seem to get me the size results I believe are possible.

quixoticelixer- 7y ago
Encoders already do this to some extent, but that is the codecs job (AV1, H264 etc) not FFmpegs.
slimscsi 7y ago
Increase the key-frame interval
hackcasual 7y ago
This might be helpful: https://video.stackexchange.com/questions/24680/what-is-keyint-and-min-keyint-and-no-scenecut https://video.stackexchange.com/questions/24680/what-is-keyi... If you're storing video only for offline viewing with minimal seeking, you can increase the iframe seperation, but if you're streaming this video, you'll need to pay the cost of including iframes to allow clients to seek or recover from dropped packets.
- nullwasamistake 7y ago
  This guy is totally right. When there's no change on screen a huge percentage of bandwidth is from iframes, essentially start over points for fast forward and network corruption. There's a tradeoff between skip/fast forward fidelity, streaming delay, and iframes. If you're not live streaming and don't care how easy it is to skip around the video increase the iframes inverval as much as you want and watch the bitrate melt away
- astrange 7y ago
  If you're streaming, you don't need to implement full I-frames; instead you can do a kind of top-to-bottom rolling refresh. The video will be corrupt until the decoder catches up, but that's OK. This is mostly used for TV broadcasts where you don't want the whole keyframe to get lost because of some brief interference. It's also good because it lowers peak bandwidth per second.

thwythwy 7y ago

Does this play nice with Python youtube-dl? [1] [2]. I want to run a python script on my computer that captures youtube audio of certain government meetings without first having to dl the entire video and convert it (while doing a bunch of other stuff before and after automatically, all without me touching anything). [1] https://stackoverflow.com/questions/27473526/download-only-audio-from-youtube-video-using-youtube-dl-in-python-script https://stackoverflow.com/questions/27473526/download-only-a... [2] https://stackoverflow.com/questions/39665160/youtube-dl-python-script-postprocessing-error-ffmpeg-codecs-arent-being-recogn https://stackoverflow.com/questions/39665160/youtube-dl-pyth...

icebraining 7y ago
Unless you need to convert the audio format, I don't think you need ffmpeg at all - youtube-dl can just download the audio stream and save it to a file. Just list the available formats from a video and choose an audio-only format.
- thwythwy 7y ago
  will try thank you
- Nullabillity 7y ago
  Also, IIRC youtube-dl will automatically re-encode it using ffmpeg if you pick an unavailable format!
- timendum 7y ago
  Insome cases youtube-dl downloads the content via ffmpeg, see [1] [1] https://github.com/ytdl-org/youtube-dl/blob/c3bcd206eb031de30179c88ac7acd806a477ceae/youtube_dl/downloader/__init__.py https://github.com/ytdl-org/youtube-dl/blob/c3bcd206eb031de3...
A2017U1 7y ago
youtube-dl -x <url> uses ffmpeg out of the box to extract mp3 audio from a video.
7y ago