[FFmpeg-devel] [PATCH v1 2/3] avcodec/bitpacked: add interlace support
Paul B Mahol
onemda at gmail.com
Wed Apr 11 09:47:40 EEST 2018
On 4/10/18, Patrick Keroulas <patrick.keroulas at savoirfairelinux.com> wrote:
> From: Damien Riegel <damien.riegel at savoirfairelinux.com>
>
> This codec is already capable of depacking some combinations of pixel
> formats and depth as defined in the RFC4175. The only difference between
> progressive and interlace is that either a packet will contain the whole
> frame, or only a field of the frame.
>
> As FFmpeg is not capable of handling fields only and recompose an
> interlaced frame from that, it has to be done by the codec. To achieve
> that, it must use two AVPacket: one for each field (top and bottom).
This is lie, FFmpeg handle fields only just fine.
>
> Signed-off-by: Damien Riegel <damien.riegel at savoirfairelinux.com>
> Signed-off-by: Patrick Keroulas <patrick.keroulas at savoirfairelinux.com>
> ---
> libavcodec/avcodec.h | 4 +++
> libavcodec/bitpacked.c | 76
> ++++++++++++++++++++++++++++++++++++++++++--------
> 2 files changed, 68 insertions(+), 12 deletions(-)
>
> diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
> index fb0c6fa..350e8d9 100644
> --- a/libavcodec/avcodec.h
> +++ b/libavcodec/avcodec.h
> @@ -1480,6 +1480,10 @@ typedef struct AVPacket {
> */
> #define AV_PKT_FLAG_DISPOSABLE 0x0010
>
> +/**
> + * The packet contains a top field.
> + */
> +#define AV_PKT_FLAG_TOP_FIELD 0x0010
>
> enum AVSideDataParamChangeFlags {
> AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_COUNT = 0x0001,
> diff --git a/libavcodec/bitpacked.c b/libavcodec/bitpacked.c
> index 85d4bdd..d81703d 100644
> --- a/libavcodec/bitpacked.c
> +++ b/libavcodec/bitpacked.c
> @@ -33,15 +33,19 @@
>
> struct BitpackedContext {
> int (*decode)(AVCodecContext *avctx, AVFrame *frame,
> - AVPacket *pkt);
> + AVPacket *pkt, int top_field);
> + AVPacket *first_field_pkt;
> };
>
> /* For this format, it's a simple passthrough */
> static int bitpacked_decode_uyvy422(AVCodecContext *avctx, AVFrame *frame,
> - AVPacket *avpkt)
> + AVPacket *avpkt, int top_field)
> {
> int ret;
>
> + if (frame->interlaced_frame)
> + return AVERROR_PATCHWELCOME;
> +
> /* there is no need to copy as the data already match
> * a known pixel format */
> frame->buf[0] = av_buffer_ref(avpkt->buf);
> @@ -56,17 +60,22 @@ static int bitpacked_decode_uyvy422(AVCodecContext
> *avctx, AVFrame *frame,
> }
>
> static int bitpacked_decode_yuv422p10(AVCodecContext *avctx, AVFrame
> *frame,
> - AVPacket *avpkt)
> + AVPacket *avpkt, int top_field)
> {
> uint64_t frame_size = (uint64_t)avctx->width * (uint64_t)avctx->height
> * 20;
> uint64_t packet_size = (uint64_t)avpkt->size * 8;
> + int interlaced = frame->interlaced_frame;
> GetBitContext bc;
> uint16_t *y, *u, *v;
> int ret, i, j;
>
> -
> - if (frame_size > packet_size)
> + /* check packet size depending on the interlaced/progressive format */
> + if (interlaced) {
> + if ((frame_size >> 1) > packet_size)
> + return AVERROR_INVALIDDATA;
> + } else if (frame_size > packet_size) {
> return AVERROR_INVALIDDATA;
> + }
>
> if (avctx->width % 2)
> return AVERROR_PATCHWELCOME;
> @@ -75,7 +84,18 @@ static int bitpacked_decode_yuv422p10(AVCodecContext
> *avctx, AVFrame *frame,
> if (ret)
> return ret;
>
> - for (i = 0; i < avctx->height; i++) {
> + /*
> + * if the frame is interlaced, the avpkt we are getting is either the
> top
> + * or the bottom field. If it's the bottom field, it contains all the
> odd
> + * lines of the recomposed frame, so we start at offset 1.
> + */
> + i = (interlaced && !top_field) ? 1 : 0;
> +
> + /*
> + * Packets from interlaced frames contain either even lines, or odd
> + * lines, so increment by two in that case.
> + */
> + for (; i < avctx->height; interlaced ? i += 2 : i++) {
> y = (uint16_t*)(frame->data[0] + i * frame->linesize[0]);
> u = (uint16_t*)(frame->data[1] + i * frame->linesize[1]);
> v = (uint16_t*)(frame->data[2] + i * frame->linesize[2]);
> @@ -100,13 +120,20 @@ static av_cold int
> bitpacked_init_decoder(AVCodecContext *avctx)
>
> if (avctx->codec_tag == MKTAG('U', 'Y', 'V', 'Y')) {
> if (avctx->bits_per_coded_sample == 16 &&
> - avctx->pix_fmt == AV_PIX_FMT_UYVY422)
> + avctx->pix_fmt == AV_PIX_FMT_UYVY422) {
> +
> + if (avctx->field_order > AV_FIELD_PROGRESSIVE) {
> + av_log(avctx, AV_LOG_ERROR, "interlaced not yet supported
> for 8-bit\n");
> + return AVERROR_PATCHWELCOME;
> + }
> +
> bc->decode = bitpacked_decode_uyvy422;
> - else if (avctx->bits_per_coded_sample == 20 &&
> - avctx->pix_fmt == AV_PIX_FMT_YUV422P10)
> + } else if (avctx->bits_per_coded_sample == 20 &&
> + avctx->pix_fmt == AV_PIX_FMT_YUV422P10) {
> bc->decode = bitpacked_decode_yuv422p10;
> - else
> + } else {
> return AVERROR_INVALIDDATA;
> + }
> } else {
> return AVERROR_INVALIDDATA;
> }
> @@ -120,24 +147,49 @@ static int bitpacked_decode(AVCodecContext *avctx,
> void *data, int *got_frame,
> struct BitpackedContext *bc = avctx->priv_data;
> int buf_size = avpkt->size;
> AVFrame *frame = data;
> + int top_field = 0;
> int res;
>
> frame->pict_type = AV_PICTURE_TYPE_I;
> frame->key_frame = 1;
>
> + if (avctx->field_order != AV_FIELD_PROGRESSIVE) {
> + top_field = avpkt->flags & AV_PKT_FLAG_TOP_FIELD;
> + frame->interlaced_frame = 1;
> + frame->top_field_first = 1;
> + }
> +
> if (avctx->pix_fmt == AV_PIX_FMT_YUV422P10) {
> res = ff_get_buffer(avctx, frame, 0);
> if (res < 0)
> return res;
> }
>
> - res = bc->decode(avctx, frame, avpkt);
> + if (frame->interlaced_frame) {
> +
> + if (top_field) {
> + bc->first_field_pkt = av_packet_clone(avpkt);
> + return 0;
> +
> + } else if (bc->first_field_pkt) {
> + /* Combine the 2 fields in a single frame.
> + * N fields/s give N/2 frames/s. */
> + res = bc->decode(avctx, frame, bc->first_field_pkt, 1);
> + res += bc->decode(avctx, frame, avpkt, 0);
> +
> + av_packet_free(&bc->first_field_pkt);
> + } else {
> + return 0;
> + }
> + } else {
> + res = bc->decode(avctx, frame, avpkt, 0);
> + }
> +
> if (res)
> return res;
>
> *got_frame = 1;
> return buf_size;
> -
> }
>
> AVCodec ff_bitpacked_decoder = {
> --
> 2.7.4
>
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
More information about the ffmpeg-devel
mailing list