[FFmpeg-devel] [PATCH] avcodec/decode: port last_pkt_props to AVFifoBuffer
James Almer
jamrial at gmail.com
Fri Dec 4 20:44:20 EET 2020
On 12/4/2020 2:08 PM, Andreas Rheinhardt wrote:
> James Almer:
>> Signed-off-by: James Almer <jamrial at gmail.com>
>> ---
>> The idea of making avpriv_packet_list_* public was not liked, and it was
>> suggested to just use AVFifoBuffer instead.
>>
>> After this, the avpriv_packet_list_* functions can be made local to
>> libavformat again.
>>
>> libavcodec/decode.c | 41 +++++++++++++++++++++++++++++------------
>> libavcodec/internal.h | 4 ++--
>> libavcodec/utils.c | 11 ++++++-----
>> 3 files changed, 37 insertions(+), 19 deletions(-)
>>
>> diff --git a/libavcodec/decode.c b/libavcodec/decode.c
>> index 5a1849f944..0550637029 100644
>> --- a/libavcodec/decode.c
>> +++ b/libavcodec/decode.c
>> @@ -145,22 +145,40 @@ fail2:
>>
>> #define IS_EMPTY(pkt) (!(pkt)->data)
>>
>> +static int copy_packet_props(void *_src, void *_dst, int size)
>> +{
>> + AVPacket *src = _src, *dst = _dst;
>> + int ret;
>> +
>> + av_init_packet(dst);
>> + ret = av_packet_copy_props(dst, src);
>> + if (ret < 0)
>> + return ret;> +
>> + dst->size = src->size; // HACK: Needed for ff_decode_frame_props().
>> + dst->data = (void*)1; // HACK: Needed for IS_EMPTY().
>> +
>> + return sizeof(*dst);
>> +}
>
> This is not how a write function for a fifo should look like: A fifo may
> need to store the beginning of a packet at the end of the fifo and the
> end of a packet at the beginning of a fifo; you can check for this by
> checking whether size is < sizeof(AVPacket).
I'm already ensuring there's always sizeof(AVPacket) bytes left before
calling av_fifo_generic_write().
> (The current implementation seems to actually only allocate multiples of
> a certain unit if all av_fifo_grow()/av_fifo_realloc2()/av_fifo_alloc()
> calls use only multiples of this unit, but it doesn't seem to be
> documented. Should probably be done as this simplifies using fifo arrays.)
>
> And apart from that: The current implementation of
> av_fifo_generic_write() does not forward errors from the write function;
> and changing this require be an API break.
Accepting a function that can return < 0 but must not be an error sounds
like an awful oversight when defining this API...
I guess i can just do the av_packet_copy_props() call in
extract_packet_props() and not use a custom function at all.
>
>> +
>> static int extract_packet_props(AVCodecInternal *avci, AVPacket *pkt)
>> {
>> int ret = 0;
>>
>> - ret = avpriv_packet_list_put(&avci->pkt_props, &avci->pkt_props_tail, pkt,
>> - av_packet_copy_props, 0);
>> + if (av_fifo_space(avci->pkt_props) < sizeof(*pkt)) {
>> + ret = av_fifo_grow(avci->pkt_props, sizeof(*pkt));
>> + if (ret < 0)
>> + return ret;
>> + }
>> +
>> + ret = av_fifo_generic_write(avci->pkt_props, pkt, sizeof(*pkt), copy_packet_props);
>> if (ret < 0)
>> return ret;
>> - avci->pkt_props_tail->pkt.size = pkt->size; // HACK: Needed for ff_decode_frame_props().
>> - avci->pkt_props_tail->pkt.data = (void*)1; // HACK: Needed for IS_EMPTY().
>>
>> + av_assert0(ret == sizeof(*pkt));
>> if (IS_EMPTY(avci->last_pkt_props)) {
>> - ret = avpriv_packet_list_get(&avci->pkt_props,
>> - &avci->pkt_props_tail,
>> - avci->last_pkt_props);
>> - av_assert0(ret != AVERROR(EAGAIN));
>> + ret = av_fifo_generic_read(avci->pkt_props, avci->last_pkt_props,
>> + sizeof(*avci->last_pkt_props), NULL);
>> }
>> return ret;
>> }
>> @@ -1721,10 +1739,9 @@ int ff_decode_frame_props(AVCodecContext *avctx, AVFrame *frame)
>> { AV_PKT_DATA_S12M_TIMECODE, AV_FRAME_DATA_S12M_TIMECODE },
>> };
>>
>> - if (IS_EMPTY(pkt))
>> - avpriv_packet_list_get(&avctx->internal->pkt_props,
>> - &avctx->internal->pkt_props_tail,
>> - pkt);
>> + if (IS_EMPTY(pkt) && av_fifo_size(avctx->internal->pkt_props) >= sizeof(*pkt))
>> + av_fifo_generic_read(avctx->internal->pkt_props,
>> + pkt, sizeof(*pkt), NULL);
>>
>> if (pkt) {
>> frame->pts = pkt->pts;
>> diff --git a/libavcodec/internal.h b/libavcodec/internal.h
>> index 17defb9b50..8a51bca2df 100644
>> --- a/libavcodec/internal.h
>> +++ b/libavcodec/internal.h
>> @@ -28,6 +28,7 @@
>>
>> #include "libavutil/buffer.h"
>> #include "libavutil/channel_layout.h"
>> +#include "libavutil/fifo.h"
>> #include "libavutil/mathematics.h"
>> #include "libavutil/pixfmt.h"
>> #include "avcodec.h"
>> @@ -145,8 +146,7 @@ typedef struct AVCodecInternal {
>> * for decoding.
>> */
>> AVPacket *last_pkt_props;
>> - AVPacketList *pkt_props;
>> - AVPacketList *pkt_props_tail;
>> + AVFifoBuffer *pkt_props;
>>
>> /**
>> * temporary buffer used for encoders to store their bitstream
>> diff --git a/libavcodec/utils.c b/libavcodec/utils.c
>> index 45295dd3ce..c81cc972dc 100644
>> --- a/libavcodec/utils.c
>> +++ b/libavcodec/utils.c
>> @@ -593,10 +593,12 @@ int attribute_align_arg avcodec_open2(AVCodecContext *avctx, const AVCodec *code
>> avci->es.in_frame = av_frame_alloc();
>> avci->ds.in_pkt = av_packet_alloc();
>> avci->last_pkt_props = av_packet_alloc();
>> + avci->pkt_props = av_fifo_alloc(sizeof(AVPacket));
>> if (!avci->compat_decode_frame || !avci->compat_encode_packet ||
>> !avci->buffer_frame || !avci->buffer_pkt ||
>> !avci->es.in_frame || !avci->ds.in_pkt ||
>> - !avci->to_free || !avci->last_pkt_props) {
>> + !avci->to_free || !avci->last_pkt_props ||
>> + !avci->pkt_props) {
>> ret = AVERROR(ENOMEM);
>> goto free_and_end;
>> }
>> @@ -1076,6 +1078,7 @@ FF_ENABLE_DEPRECATION_WARNINGS
>> av_packet_free(&avci->compat_encode_packet);
>> av_packet_free(&avci->buffer_pkt);
>> av_packet_free(&avci->last_pkt_props);
>> + av_fifo_freep(&avci->pkt_props);
>>
>> av_packet_free(&avci->ds.in_pkt);
>> av_frame_free(&avci->es.in_frame);
>> @@ -1116,8 +1119,7 @@ void avcodec_flush_buffers(AVCodecContext *avctx)
>> av_packet_unref(avci->buffer_pkt);
>>
>> av_packet_unref(avci->last_pkt_props);
>> - avpriv_packet_list_free(&avci->pkt_props,
>> - &avci->pkt_props_tail);
>> + av_fifo_reset(avci->pkt_props);
>>
>
> The packets in the fifo may contain side-data (because
> av_packet_copy_props() copies it) and if so, it leaks here.
Right. Will drain it, then.
>
>> av_frame_unref(avci->es.in_frame);
>> av_packet_unref(avci->ds.in_pkt);
>> @@ -1180,8 +1182,7 @@ av_cold int avcodec_close(AVCodecContext *avctx)
>> av_packet_free(&avctx->internal->compat_encode_packet);
>> av_packet_free(&avctx->internal->buffer_pkt);
>> av_packet_free(&avctx->internal->last_pkt_props);
>> - avpriv_packet_list_free(&avctx->internal->pkt_props,
>> - &avctx->internal->pkt_props_tail);
>> + av_fifo_freep(&avctx->internal->pkt_props);
>>
>> av_packet_free(&avctx->internal->ds.in_pkt);
>> av_frame_free(&avctx->internal->es.in_frame);
>>
>
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