Re: [FFmpeg-devel] [PATCH] avformat/flvenc: avoid an extra allocate

[James Almer <jamrial@gmail.com>]

On 4/6/2023 5:11 PM, Zhao Zhili wrote:
> From: Zhao Zhili <zhilizhao@tencent.com>
> 
> ---
>   libavformat/flvenc.c | 24 +++++++-----------------
>   1 file changed, 7 insertions(+), 17 deletions(-)
> 
> diff --git a/libavformat/flvenc.c b/libavformat/flvenc.c
> index a7b5efde4b..3a686b73d7 100644
> --- a/libavformat/flvenc.c
> +++ b/libavformat/flvenc.c
> @@ -117,12 +117,9 @@ typedef struct FLVContext {
>       AVCodecParameters *data_par;
>   
>       int flags;
> +    uint32_t last_ts[3];

I understand that timestamps are 32bit on flv, but things are pretty 
inconsistent type wise across the entire file. This used to be int64_t 
and you're changing it to uint32_t. Some parameters expect an unsigned 
int and others an int64_t. It would be nice to choose a single type and 
use it everywhere.
The source for all of them is apparently pkt->dts, which is int64_t, so 
I'd use that everywhere and ensure its value is <= INT32_MAX or <= 
UINT32_MAX depending on how you store it.

>   } FLVContext;
>   
> -typedef struct FLVStreamContext {
> -    int64_t last_ts;    ///< last timestamp for each stream
> -} FLVStreamContext;
> -
>   static int get_audio_flags(AVFormatContext *s, AVCodecParameters *par)
>   {
>       int flags = (par->bits_per_coded_sample == 16) ? FLV_SAMPLESSIZE_16BIT
> @@ -611,7 +608,7 @@ static int flv_init(struct AVFormatContext *s)
>   
>       for (i = 0; i < s->nb_streams; i++) {
>           AVCodecParameters *par = s->streams[i]->codecpar;
> -        FLVStreamContext *sc;
> +
>           switch (par->codec_type) {
>           case AVMEDIA_TYPE_VIDEO:
>               if (s->streams[i]->avg_frame_rate.den &&
> @@ -675,12 +672,7 @@ static int flv_init(struct AVFormatContext *s)
>               return AVERROR(EINVAL);
>           }
>           avpriv_set_pts_info(s->streams[i], 32, 1, 1000); /* 32 bit pts in ms */
> -
> -        sc = av_mallocz(sizeof(FLVStreamContext));
> -        if (!sc)
> -            return AVERROR(ENOMEM);
> -        s->streams[i]->priv_data = sc;
> -        sc->last_ts = -1;
> +        flv->last_ts[i] = -1;
>       }
>   
>       flv->delay = AV_NOPTS_VALUE;
> @@ -783,10 +775,9 @@ end:
>           /* Add EOS tag */
>           for (i = 0; i < s->nb_streams; i++) {
>               AVCodecParameters *par = s->streams[i]->codecpar;
> -            FLVStreamContext *sc = s->streams[i]->priv_data;
>               if (par->codec_type == AVMEDIA_TYPE_VIDEO &&
>                       (par->codec_id == AV_CODEC_ID_H264 || par->codec_id == AV_CODEC_ID_MPEG4))
> -                put_eos_tag(pb, sc->last_ts, par->codec_id);
> +                put_eos_tag(pb, flv->last_ts[i], par->codec_id);
>           }
>       }
>   
> @@ -821,7 +812,6 @@ static int flv_write_packet(AVFormatContext *s, AVPacket *pkt)
>       AVIOContext *pb      = s->pb;
>       AVCodecParameters *par = s->streams[pkt->stream_index]->codecpar;
>       FLVContext *flv      = s->priv_data;
> -    FLVStreamContext *sc = s->streams[pkt->stream_index]->priv_data;
>       unsigned ts;
>       int size = pkt->size;
>       uint8_t *data = NULL;
> @@ -919,13 +909,13 @@ static int flv_write_packet(AVFormatContext *s, AVPacket *pkt)
>       }
>   
>       /* check Speex packet duration */
> -    if (par->codec_id == AV_CODEC_ID_SPEEX && ts - sc->last_ts > 160)
> +    if (par->codec_id == AV_CODEC_ID_SPEEX && ts - flv->last_ts[pkt->stream_index] > 160)
>           av_log(s, AV_LOG_WARNING, "Warning: Speex stream has more than "
>                                     "8 frames per packet. Adobe Flash "
>                                     "Player cannot handle this!\n");
>   
> -    if (sc->last_ts < ts)
> -        sc->last_ts = ts;
> +    if (flv->last_ts[pkt->stream_index] < ts)
> +        flv->last_ts[pkt->stream_index] = ts;
>   
>       if (size + flags_size >= 1<<24) {
>           av_log(s, AV_LOG_ERROR, "Too large packet with size %u >= %u\n",
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