[FFmpeg-devel] avcodec/libopusenc: reload packet loss at encode

An estimation of packet loss is required by libopus to compute its FEC
data. Currently, this estimation is constant, and can not be changed
after configuration. This means an application using libopus through
ffmpeg can not adapt the packet loss estimation when the network
quality degrades.

This patch makes the encoder reload the packet_loss AVOption before
encoding samples, if fec is enabled. This way an application can modify
the packet loss estimation by changing the AVOption. Typical use-case
is a RTP stream, where packet loss can be estimated from RTCP packets.

Signed-off-by: Philip-Dylan Gleonec <philip-dylan.gleonec@savoirfairelinux.com>
---
 libavcodec/libopusenc.c | 9 +++++++++
 1 file changed, 9 insertions(+)

Le 16/02/2021 à 15:04, Philip-Dylan Gleonec a écrit :
> An estimation of packet loss is required by libopus to compute its FEC
> data. Currently, this estimation is constant, and can not be changed
> after configuration. This means an application using libopus through
> ffmpeg can not adapt the packet loss estimation when the network
> quality degrades.
> 
> This patch makes the encoder reload the packet_loss AVOption before
> encoding samples, if fec is enabled. This way an application can modify
> the packet loss estimation by changing the AVOption. Typical use-case
> is a RTP stream, where packet loss can be estimated from RTCP packets.
> 
> Signed-off-by: Philip-Dylan Gleonec <philip-dylan.gleonec@savoirfairelinux.com>
> ---
>   libavcodec/libopusenc.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
> 
> diff --git a/libavcodec/libopusenc.c b/libavcodec/libopusenc.c
> index 70d17f802b..c18e8ae7fa 100644
> --- a/libavcodec/libopusenc.c
> +++ b/libavcodec/libopusenc.c
> @@ -460,6 +460,15 @@ static int libopus_encode(AVCodecContext *avctx, AVPacket *avpkt,
>       int ret;
>       int discard_padding;
>   
> +    if (opus->opts.fec) {
> +        ret = opus_multistream_encoder_ctl(opus->enc,
> +                                           OPUS_SET_PACKET_LOSS_PERC(opus->opts.packet_loss));
> +        if (ret != OPUS_OK)
> +            av_log(avctx, AV_LOG_WARNING,
> +                   "Unable to set expected packet loss percentage: %s\n",
> +                   opus_strerror(ret));
> +    }
> +
>       if (frame) {
>           ret = ff_af_queue_add(&opus->afq, frame);
>           if (ret < 0)
> 

Hello,

Is someone interested in picking this up, or is there some correction I 
should make to this patch ?

Regards,
Philip-Dylan Gleonec

Mar 3, 2021, 16:50 by philip-dylan.gleonec@savoirfairelinux.com:

> Le 16/02/2021 à 15:04, Philip-Dylan Gleonec a écrit :
>
>> An estimation of packet loss is required by libopus to compute its FEC
>> data. Currently, this estimation is constant, and can not be changed
>> after configuration. This means an application using libopus through
>> ffmpeg can not adapt the packet loss estimation when the network
>> quality degrades.
>>
>> This patch makes the encoder reload the packet_loss AVOption before
>> encoding samples, if fec is enabled. This way an application can modify
>> the packet loss estimation by changing the AVOption. Typical use-case
>> is a RTP stream, where packet loss can be estimated from RTCP packets.
>>
>> Signed-off-by: Philip-Dylan Gleonec <philip-dylan.gleonec@savoirfairelinux.com>
>> ---
>>  libavcodec/libopusenc.c | 9 +++++++++
>>  1 file changed, 9 insertions(+)
>>
>> diff --git a/libavcodec/libopusenc.c b/libavcodec/libopusenc.c
>> index 70d17f802b..c18e8ae7fa 100644
>> --- a/libavcodec/libopusenc.c
>> +++ b/libavcodec/libopusenc.c
>> @@ -460,6 +460,15 @@ static int libopus_encode(AVCodecContext *avctx, AVPacket *avpkt,
>>  int ret;
>>  int discard_padding;
>>  +    if (opus->opts.fec) {
>> +        ret = opus_multistream_encoder_ctl(opus->enc,
>> +                                           OPUS_SET_PACKET_LOSS_PERC(opus->opts.packet_loss));
>> +        if (ret != OPUS_OK)
>> +            av_log(avctx, AV_LOG_WARNING,
>> +                   "Unable to set expected packet loss percentage: %s\n",
>> +                   opus_strerror(ret));
>> +    }
>> +
>>  if (frame) {
>>  ret = ff_af_queue_add(&opus->afq, frame);
>>  if (ret < 0)
>>
>
> Hello,
>
> Is someone interested in picking this up, or is there some correction I should make to this patch ?
>

Could you check if the option value has changed in between calls
to encode and only reset the packet loss value if it has?
With that change, patch looks good.