Re: [FFmpeg-user] Convert flv to mp4. Bad video quality
Thank you Carl for your clarification. I obtain good results using -q:v 4 Best, Prof. Flavio Sartoretto gia' Docente di Calcolo Scientifico Universita' Ca' Foscari Venezia On Fri, May 28, 2021 at 5:24 PM Carl Eugen Hoyos wrote: > > > > > > > Am 28.05.2021 um 11:44 schrieb Michael Koch : > > > > Am 28.05.2021 um 11:25 schrieb Flavio Sartoretto: > >> I use ffmpeg in order to convert fname.flv video to mp4: > >> ffmpeg -i fname.flv -c:v mpeg4 -copyts -loglevel verbose fname.mp4 > >> > >> The video quality of my output is bad. How can I improve it? > > > > Add -q:v 1 to your command line. The number does specify the compression > > ratio. 0 ist best quality and 9 is highest compression. > > This is (nearly) completely wrong: > 9 is still high quality, highest compression happens at a much higher value. > Old MEncoder documentation recommends not use a value lower than 2, sane > values start between 5 and 10. > To Flavio: > The answer to your question depends on your use case: Setting a constant > quantiser as suggested leads to output more similar to constant quality as is > possible with x264 (and newer encoders) and is likely a good idea nowadays, > the alternative is setting a bitrate, this should be combined with two-pass > encoding and leads to the best quality - file size relation (which should be > less relevant if you don’t write to a CD). > > Carl Eugen > ___ > ffmpeg-user mailing list > ffmpeg-user@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-user > > To unsubscribe, visit link above, or email > ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe". ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Convert flv to mp4. Bad video quality
On 2021-05-28 21:19, Michael Koch wrote: Am 28.05.2021 um 17:18 schrieb Carl Eugen Hoyos: This is (nearly) completely wrong: 9 is still high quality, highest compression happens at a much higher value. Old MEncoder documentation recommends not use a value lower than 2, sane values start between 5 and 10. This is an important information and should be added to the documentation. The -q option is missing in chapter 16.16.1 in ffmpeg-all.html 16.16.1 is libxvid which is an external MPEG-4 Part 2 encoder,. The OP specified the native encoder, which isn't documented and is fairly low on my list. Regards, Gyan ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Convert flv to mp4. Bad video quality
Am 28.05.2021 um 17:18 schrieb Carl Eugen Hoyos: This is (nearly) completely wrong: 9 is still high quality, highest compression happens at a much higher value. Old MEncoder documentation recommends not use a value lower than 2, sane values start between 5 and 10. This is an important information and should be added to the documentation. The -q option is missing in chapter 16.16.1 in ffmpeg-all.html Michael ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Convert flv to mp4. Bad video quality
> Am 28.05.2021 um 11:44 schrieb Michael Koch : > > Am 28.05.2021 um 11:25 schrieb Flavio Sartoretto: >> I use ffmpeg in order to convert fname.flv video to mp4: >> ffmpeg -i fname.flv -c:v mpeg4 -copyts -loglevel verbose fname.mp4 >> >> The video quality of my output is bad. How can I improve it? > > Add -q:v 1 to your command line. The number does specify the compression > ratio. 0 ist best quality and 9 is highest compression. This is (nearly) completely wrong: 9 is still high quality, highest compression happens at a much higher value. Old MEncoder documentation recommends not use a value lower than 2, sane values start between 5 and 10. To Flavio: The answer to your question depends on your use case: Setting a constant quantiser as suggested leads to output more similar to constant quality as is possible with x264 (and newer encoders) and is likely a good idea nowadays, the alternative is setting a bitrate, this should be combined with two-pass encoding and leads to the best quality - file size relation (which should be less relevant if you don’t write to a CD). Carl Eugen ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Convert flv to mp4. Bad video quality
Thank you Rick. Michael Koch suggested me to use -q:v 1, which is ok! Thanks anyway! Prof. Flavio Sartoretto gia' Docente di Calcolo Scientifico Universita' Ca' Foscari Venezia On Fri, May 28, 2021 at 2:58 PM Rick Keniuk wrote: > > Im not sure about the FFMPEG command but couldn't you check if the original > FLV is already h.264 video and AAC audio and directly copy? > > On Fri, May 28, 2021, 4:31 AM Flavio Sartoretto < > flavio.sartoretto1...@gmail.com> wrote: > > > I use ffmpeg in order to convert fname.flv video to mp4: > > ffmpeg -i fname.flv -c:v mpeg4 -copyts -loglevel verbose fname.mp4 > > > > The video quality of my output is bad. How can I improve it? > > > > Best regards, > > Prof. Flavio Sartoretto > > gia' Docente di Calcolo Scientifico > > Universita' Ca' Foscari Venezia > > ___ > > ffmpeg-user mailing list > > ffmpeg-user@ffmpeg.org > > https://ffmpeg.org/mailman/listinfo/ffmpeg-user > > > > To unsubscribe, visit link above, or email > > ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe". > > > ___ > ffmpeg-user mailing list > ffmpeg-user@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-user > > To unsubscribe, visit link above, or email > ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe". ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Convert flv to mp4. Bad video quality
Thank you Ulf for your suggestion. Michael Koch suggested me to use -q:v 1, which is ok! Thanks anyway! Prof. Flavio Sartoretto gia' Docente di Calcolo Scientifico Universita' Ca' Foscari Venezia On Fri, May 28, 2021 at 12:02 PM Ulf Zibis wrote: > > > Am 28.05.21 um 11:44 schrieb Michael Koch: > > Am 28.05.2021 um 11:25 schrieb Flavio Sartoretto: > >> I use ffmpeg in order to convert fname.flv video to mp4: > >> ffmpeg -i fname.flv -c:v mpeg4 -copyts -loglevel verbose fname.mp4 > >> > >> The video quality of my output is bad. How can I improve it? > > > > Add -q:v 1 to your command line. The number does specify the compression > > ratio. 0 ist best quality and 9 is highest compression. > > Alternatively you may drop "-c:v mpeg4". Then libx264 is used instead FFmpegs > internal mpeg4 encoder by default and you will get good quality. > > -Ulf > > ___ > ffmpeg-user mailing list > ffmpeg-user@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-user > > To unsubscribe, visit link above, or email > ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe". ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Convert flv to mp4. Bad video quality
Thank you very much, Michael! It works! Prof. Flavio Sartoretto gia' Docente di Calcolo Scientifico Universita' Ca' Foscari Venezia On Fri, May 28, 2021 at 11:44 AM Michael Koch wrote: > > Am 28.05.2021 um 11:25 schrieb Flavio Sartoretto: > > I use ffmpeg in order to convert fname.flv video to mp4: > > ffmpeg -i fname.flv -c:v mpeg4 -copyts -loglevel verbose fname.mp4 > > > > The video quality of my output is bad. How can I improve it? > > Add -q:v 1 to your command line. The number does specify the compression > ratio. 0 ist best quality and 9 is highest compression. > > Michael > > ___ > ffmpeg-user mailing list > ffmpeg-user@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-user > > To unsubscribe, visit link above, or email > ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe". ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Convert flv to mp4. Bad video quality
Im not sure about the FFMPEG command but couldn't you check if the original FLV is already h.264 video and AAC audio and directly copy? On Fri, May 28, 2021, 4:31 AM Flavio Sartoretto < flavio.sartoretto1...@gmail.com> wrote: > I use ffmpeg in order to convert fname.flv video to mp4: > ffmpeg -i fname.flv -c:v mpeg4 -copyts -loglevel verbose fname.mp4 > > The video quality of my output is bad. How can I improve it? > > Best regards, > Prof. Flavio Sartoretto > gia' Docente di Calcolo Scientifico > Universita' Ca' Foscari Venezia > ___ > ffmpeg-user mailing list > ffmpeg-user@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-user > > To unsubscribe, visit link above, or email > ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe". > ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Convert flv to mp4. Bad video quality
Am 28.05.21 um 11:44 schrieb Michael Koch: Am 28.05.2021 um 11:25 schrieb Flavio Sartoretto: I use ffmpeg in order to convert fname.flv video to mp4: ffmpeg -i fname.flv -c:v mpeg4 -copyts -loglevel verbose fname.mp4 The video quality of my output is bad. How can I improve it? Add -q:v 1 to your command line. The number does specify the compression ratio. 0 ist best quality and 9 is highest compression. Alternatively you may drop "-c:v mpeg4". Then libx264 is used instead FFmpegs internal mpeg4 encoder by default and you will get good quality. -Ulf ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Convert flv to mp4. Bad video quality
Am 28.05.2021 um 11:25 schrieb Flavio Sartoretto: I use ffmpeg in order to convert fname.flv video to mp4: ffmpeg -i fname.flv -c:v mpeg4 -copyts -loglevel verbose fname.mp4 The video quality of my output is bad. How can I improve it? Add -q:v 1 to your command line. The number does specify the compression ratio. 0 ist best quality and 9 is highest compression. Michael ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
[FFmpeg-user] Convert flv to mp4. Bad video quality
I use ffmpeg in order to convert fname.flv video to mp4: ffmpeg -i fname.flv -c:v mpeg4 -copyts -loglevel verbose fname.mp4 The video quality of my output is bad. How can I improve it? Best regards, Prof. Flavio Sartoretto gia' Docente di Calcolo Scientifico Universita' Ca' Foscari Venezia ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
