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• Can somebody compare the decoding speed of popular audio formats ? [on hold]

  23 novembre 2017, par puppon -su

  People usually quote compression ratio, but I’m interested in how well they perform on old computers and mobile phones. I’m interested in cpu usage, battery usage, and if they require/benefit from SIMD.

  I’m not sure if it still matters by now, everyone seems to buy new hardware every few years.

• libffmpeg writes bad mp4 file if the RTSP stream loses packets

  5 avril 2017, par user92238

  I’m working with libffmpeg in iOS, using it to open an RTSP stream and save the data to a file.

  I’ve been able to successfully save video files in both .mp4 and .mov formats, but there is a problem.

  If the RTSP stream is perfect — that is, if there are no dropped packets — then the resulting file is fine. I can play it in a player, and I can even transcode it using an AVAssetExportSession.

  The problem is, I’m dealing with a wireless camera that sends data over UDP only, so there are often dropped packets. When a dropped packet occurs, the resulting file has a big glitch in it : even if it’s just one or two packets, the playback freezes for about 12 seconds. Also, I cannot use AVAssetExportSession with these files. It fails, reporting a decoding problem.

  I feel like there must be some way I can cause ffmpeg to write a valid mp4 file when packets are missing. I don’t care what happens, whether the missing packets are simply deleted from the file or if they are replaced with something, I just don’t want a 12 second freeze.

  For what it’s worth, if I take the file off of my iOS device and play it on my computer, it plays fine. There’s a small glitch where the frame was dropped, but it doesn’t freeze for 12 seconds or anything.

  Thanks.

• FFMPEG realtime streaming using a remote m3u8

  8 avril 2016, par JJ The Second

  Good morning chaps,

  I’ve been doing a long term research to do DRM solution for my client and we are almost there, here is what we’d like to achieve and please accept my lack of understanding, Im well new to FFMPEG and there are so many questions already asked but I’m not sure if they cover my questions.

  Objectives :

  1- To record and stream (real-time) m3u8 from a remote server : We have access to more than 3000 HLS streams (b2b project) therefore we would need to record and stream m3u8 in real-time. Currently I am able to record to mp4 or mkv but don’t understand how to stream real time

  2- Stream using HL264 : We would need to make sure streams play on all devices, based on my understanding this is the correct format to use, is this correct, more than happy to hear your comments

  3- Delivery to be in 3 different resolutions, HD, 488 and 380 : This is all about sizes, it is unlikely that my users would stream using mobile devices (GA says only 32000 using mobile) but still I need to make sure there are no restrictions to users

  Questions :

  1- I’ve seen lots of tutorials with regards to recording m3u8, converting to mp4 or .ts files, so I’m not sure how this works, do I need to export my recording to .ts files and merge them again ? If this is the case, isn’t this going to have delay in streaming ?

  2- By doing this, am I using my bandwidth or source of m3u8 ?

  3- If converting to .ts then would you please let me know how I can achieve this ?

  Please note, my recording are (for now) all m3u8 and I need to stream as m3u8 at the same time.

  I have latest version of FFMPEG installed on Ubuntu 14.4 TLS

  Thank you all in advance and happy Friday !