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• Firefox and Internet explorer mp4 playback issue

  29 juin 2015, par Mårten Sjö

  I use a tool for recording desktop videos.

  I use the same settings in the tool and same resolution and record two different videos.

  http://www.mindmigma.com/users/fb-fac3b0ok/video3.mp4
  http://www.mindmigma.com/users/fb-fac3b0ok/video4.mp4

  Both of those videos can be played with Google Chrome version 31.

  But only video3.mp4 can be played with Firefox version 27 and Internet Explorer 11

  When i make videos it feels like a random pattern if a video will be playable or not. How can this be is the video4.mp4 damaged somehow ?

  It feels so wierd when you use the same settings and its an 50% chance the video will play in Firefox and IE.

  Would be really glad if i could get some help.
  Thanks in advance !

  /Marten S

• ffmpeg encoding sample wanted ?

  24 juin 2015, par Rella

  I found this tutorial about ffmpeg the thing i do not get is how to encode video.

  can any one, please provide a tutorial.. with explanations for that ? (not that i dont get this official one but i’d love to see more comments)

• FFmpeg 5 C api codec : how many times will EOF be returned by the receiving end ?

  3 février 2024, par Guanyuming He

  Edit : I may have written my questions unclearly at first, so I rewrote them. Sorry if you had found my questions confusing.

  


  I'm new to FFmpeg api programming (I'm using version 5.1) and am learning from the documentation and official examples.

  


  In the documentation page about send/receive encoding and decoding API overview, end of stream situation is discussed briefly :

  


  


  End of stream situations. These require "flushing" (aka draining) the codec, as the codec might buffer multiple frames or packets internally for performance or out of necessity (consider B-frames). This is handled as follows :

  


  


  


  Instead of valid input, send NULL to the avcodec_send_packet() (decoding) or avcodec_send_frame() (encoding) functions. This will enter draining mode.
Call avcodec_receive_frame() (decoding)
or avcodec_receive_packet() (encoding) in a loop until AVERROR_EOF is returned. The functions will not return AVERROR(EAGAIN), unless you forgot to enter draining mode.
Before decoding can be resumed again, the codec has to be reset with avcodec_flush_buffers().

  


  


  As I understand it, when I get AVERROR_EOF, I have reached a special point where I need to drain buffered data from the codec and finally reset the codec with avcodec_flush_buffers(). Without doing it, I cannot continue decoding/encoding.

  


  Is my understanding correct ?

  


  If so, then I have some questions :

  


  

  1. How many times at most can EOF be returned by the receiving end during one complete process, for example, decoding ?

  


  2. If the answer to the first question is infinity, then : If I received an EOF from the receiving end when I already finished sending data (e.g. when after EOF is returned by av_read_frame()), how should I tell if it's really finished ? Here there is no return code only for indicating if the receiving is finished.

  


  3. The data returned from the receive_... functions during draining, should I take them as valid ?

  


  


  I might have found answers to those in the official examples, but I'm not sure if the answer is universally true. I noticed that in some official examples, like in transcode_aac.c, draining is only done for the first EOF reached, and then after the second one is received, it is regarded that there are really nothing left. Any data received during draining is also written to the final output.

  


  Am I correct on interpreting the example ? If so, can I say that the answer to question 1 is once, and the answer to question 3 is yes ?

  


  I appreciate your response and time in advance. :)