[FFmpeg-devel] [PATCH 1/5] avformat/av1dec: Set position of AVPackets given to BSF

[James Almer]

On 8/22/2021 8:20 AM, Andreas Rheinhardt wrote:
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>
> ---
>   libavformat/av1dec.c | 44 +++++++++++++++-----------------------------
>   1 file changed, 15 insertions(+), 29 deletions(-)
> 
> diff --git a/libavformat/av1dec.c b/libavformat/av1dec.c
> index f6c575069e..e021615c1f 100644
> --- a/libavformat/av1dec.c
> +++ b/libavformat/av1dec.c
> @@ -22,7 +22,6 @@
>   #include "config.h"
>   
>   #include "libavutil/common.h"
> -#include "libavutil/fifo.h"
>   #include "libavutil/opt.h"
>   #include "libavcodec/av1_parse.h"
>   #include "libavcodec/bsf.h"
> @@ -299,7 +298,6 @@ typedef struct ObuContext {
>       const AVClass *class;
>       AVBSFContext *bsf;
>       AVRational framerate;
> -    AVFifoBuffer *fifo;
>   } ObuContext;
>   
>   //For low overhead obu, we can't foresee the obu size before we parsed the header.
> @@ -372,9 +370,6 @@ static int obu_probe(const AVProbeData *p)
>   static int obu_read_header(AVFormatContext *s)
>   {
>       ObuContext *c = s->priv_data;
> -    c->fifo = av_fifo_alloc(MAX_OBU_HEADER_SIZE);
> -    if (!c->fifo)
> -        return AVERROR(ENOMEM);
>       return read_header(s, &c->framerate, &c->bsf, c);
>   }
>   
> @@ -383,37 +378,26 @@ static int obu_get_packet(AVFormatContext *s, AVPacket *pkt)
>       ObuContext *c = s->priv_data;
>       uint8_t header[MAX_OBU_HEADER_SIZE + AV_INPUT_BUFFER_PADDING_SIZE];
>       int64_t obu_size;
> -    int size = av_fifo_space(c->fifo);
> +    int size;
>       int ret, len, type;
>   
> -    av_fifo_generic_write(c->fifo, s->pb, size,
> -                          (int (*)(void*, void*, int))avio_read);
> -    size = av_fifo_size(c->fifo);
> -    if (!size)
> -        return 0;
> -
> -    av_fifo_generic_peek(c->fifo, header, size, NULL);
> +    if ((ret = ffio_ensure_seekback(s->pb, MAX_OBU_HEADER_SIZE)) < 0)
> +        return ret;
> +    size = avio_read(s->pb, header, MAX_OBU_HEADER_SIZE);
> +    if (size < 0)
> +        return size;
>   
>       len = read_obu_with_size(header, size, &obu_size, &type);
>       if (len < 0) {
>           av_log(c, AV_LOG_ERROR, "Failed to read obu\n");
>           return len;
>       }
> +    avio_seek(s->pb, -size, SEEK_CUR);
>   
> -    ret = av_new_packet(pkt, len);
> -    if (ret < 0) {
> -        av_log(c, AV_LOG_ERROR, "Failed to allocate packet for obu\n");
> -        return ret;
> -    }
> -    size = FFMIN(size, len);
> -    av_fifo_generic_read(c->fifo, pkt->data, size, NULL);
> -    len -= size;
> -    if (len > 0) {
> -        ret = avio_read(s->pb, pkt->data + size, len);
> -        if (ret != len) {
> -            av_log(c, AV_LOG_ERROR, "Failed to read %d frome file\n", len);
> -            return ret < 0 ? ret : AVERROR_INVALIDDATA;
> -        }
> +    ret = av_get_packet(s->pb, pkt, len);
> +    if (ret != len) {
> +        av_log(c, AV_LOG_ERROR, "Failed to get packet for obu\n");
> +        return ret < 0 ? ret : AVERROR_INVALIDDATA;
>       }
>       return 0;
>   }
> @@ -425,7 +409,10 @@ static int obu_read_packet(AVFormatContext *s, AVPacket *pkt)
>   
>       while (1) {
>           ret = obu_get_packet(s, pkt);
> -        if (ret < 0)
> +        /* In case of AVERROR_EOF we need to flush the BSF. Conveniently
> +         * obu_get_packet() returns a blank pkt in this case which
> +         * can be used to signal that the BSF should be flushed. */
> +        if (ret < 0 && ret != AVERROR_EOF)
>               return ret;
>           ret = av_bsf_send_packet(c->bsf, pkt);
>           if (ret < 0) {
> @@ -448,7 +435,6 @@ static int obu_read_close(AVFormatContext *s)
>   {
>       ObuContext *c = s->priv_data;
>   
> -    av_fifo_freep(&c->fifo);
>       av_bsf_free(&c->bsf);
>       return 0;
>   }

LGTM.